The Red River Compact (or Compact) is a congressionally sanctioned agreement that allocates water rights within the Red River basin among the States of Oklahoma, Texas, Arkansas, and Louisiana. The area it governs is divided into five separate subdivisions called “Reaches,” each of which is further divided into smaller “subbasins.” At issue here are rights under the Compact to water located in Oklahoma’s portion of Reach II, subbasin 5. In Reach II, the Compact— recognizing that Louisiana lacks suitable reservoir sites to store water during high flow periods and that the upstream States (Texas, Oklahoma, and Arkansas) were unwilling to release their own stored water for the benefit of a downstream State—granted control over the water in four upstream subbasins (subbasins 1 through 4) to the States in which each subbasin is located and required that water in a fifth subbasin, subbasin 5, be allowed to flow to Louisiana at certain minimum levels. Section 5.05(b)(1) of the Compact gives the States “equal rights” to the use of subbasin 5’s waters when the flow is 3,000 cubic feet per second (CFS) or more, “provided no state is entitled to more than 25 percent of the water in excess of 3,000 [CFS].” Under the Compact, States are also entitled to continue with their intrastate water administration. Petitioner Tarrant Regional Water District (Tarrant) is a Texas state agency responsible for providing water to north-central Texas and its rapidly growing population. After unsuccessfully attempting to purchase water from Oklahoma and others, Tarrant sought a water resource permit from the Oklahoma Water Resources Board (OWRB), respondents here, to take surface water from a tributary of the Red River at a point located in Oklahoma’s portion of subbasin 5 2 TARRANT REGIONAL WATER DIST. v. HERRMANN Syllabus of Reach II. Knowing that the OWRB would likely deny its permit application because of Oklahoma water laws that effectively prevent out-of-state applicants from taking or diverting water from within Oklahoma’s borders, Tarrant filed suit in federal court simultaneously with its permit application, seeking to enjoin the OWRB’s enforcement of the state statutes on grounds that they were pre-empted by federal law in the form of the Compact and violated the Commerce Clause by discriminating against interstate commerce in water. The District Court granted summary judgment for the OWRB, and the Tenth Circuit affirmed. Held: 1. The Compact does not pre-empt the Oklahoma water statutes. Pp. 9–22. (a) Tarrant claims that §5.05(b)(1) creates a borderless common in subbasin 5 in which each of the signatory States may cross each other’s boundaries to access a shared pool of water. Tarrant observes that §5.05(b)(1)’s “equal rights” language grants each State an equal entitlement to subbasin 5’s waters, subject to a 25 percent cap, and argues that its silence concerning state lines indicates that the Compact’s drafters did not intend the provision to allocate water according to state borders. The OWRB counters that §5.05(b)(1)’s “equal rights” afford each State an equal opportunity to use subbasin 5’s excess water within each State’s own borders, but that its silence on cross-border rights indicates that the Compact’s drafters had no intention to create any such rights in the signatory States. Pp. 9–11. (b) Because interstate compacts are construed under contractlaw principles, see Texas v. New Mexico, 482 U. S. 124, 128, the Court begins by examining the Compact’s express terms as the best indication of the parties’ intent. However, §5.05(b)(1)’s silence is, at the very least, ambiguous regarding cross-border rights under the Compact, so the Court turns to other interpretive tools to shed light on the drafters’ intent. Three things persuade the Court that the Compact did not grant cross-border rights: the well-established principle that States do not easily cede their sovereign powers; the fact that other interstate water compacts have treated cross-border rights explicitly; and the parties’ course of dealing. Pp. 11–22. (1) The sovereign States possess an “absolute right to all their navigable waters and the soils under them for their own common use.” Martin v. Lessee of Waddell, 16 Pet. 367, 410. So, for example, “ ‘[a] court deciding a question of title to [a] bed of navigable water [within a State’s boundaries] must . . . begin with a strong presumption’ against defeat of a State’s title.” United States v. Alaska, 521 U. S. 1, 34. It follows, then, that “[i]f any inference at all is to be drawn from” silence in compacts touching on the States’ authority to Cite as: 569 U. S. ____ (2013) 3 Syllabus control their waters, “it is that each State was left to regulate the activities of her own citizens.” Virginia v. Maryland, 540 U. S. 56, 67. Tarrant contends that §5.05(b)(1)’s silence infers that the signatory States dispensed with the core state prerogative to control water within its borders. But since States rarely relinquish their sovereign powers, the better understanding is that there would be a clear indication of such devolution, not inscrutable silence. Tarrant counters that its interpretation would not intrude on any sovereign prerogative of Oklahoma, which would retain its authority to regulate the water within its borders. But adopting Tarrant’s reading would necessarily entail assuming that Oklahoma and three other States silently surrendered substantial control over their waters when they agreed to the Compact. Pp. 14–16. (2) Looking to the customary practices employed in other interstate compacts also helps in ascertaining the parties’ intent. See, e.g., Alabama v. North Carolina, 560 U. S. 330, ___. Many compacts feature unambiguous language permitting signatory States to cross each other’s borders to fulfill obligations under the compacts, and many provide for the terms and mechanics of how such relationships will operate. The absence of comparable provisions in the Red River Compact strongly suggests that cross-border rights were never intended to be part of the agreement. Tarrant claims that not all interstate compacts have such explicit language, but cites only one such compact, and even it sets out a detailed scheme that would apply to any contemplated diversions. Similarly, even if §2.05(d) of the Compact, which gives “[e]ach Signatory State . . . the right to” “[u]se the bed and banks of the Red River and its tributaries to convey stored water, imported or exported water, and water apportioned according to this Compact,” is read to establish cross-border diversions, it does so through express language, not through an inference from silence. Pp. 16–20. (3) The parties’ conduct under the Compact also undermines Tarrant’s position. See Alabama v. North Carolina, 560 U. S., at ___. Once the Compact was approved in 1980, no signatory State pressed for a cross-border diversion until Tarrant filed suit in 2007. And Tarrant’s earlier offer to purchase water from Oklahoma was a strange decision if Tarrant believed the Compact entitled it to demand water without payment. Nor is there any indication that Tarrant, any other Texas agency, or Texas itself previously made any mention of cross-border rights within the Compact; and none of the other signatory States has ever made such a claim. P. 20. (4) Tarrant’s remaining arguments—that its interpretation is necessary to realize the “structure and purpose of Reach II”; and that §5.05(b)(1)’s 25 percent cap on each State’s access to subbasin 5’s ex-4 TARRANT REGIONAL WATER DIST. v. HERRMANN Syllabus cess water implies that if a State cannot access sufficient water within its borders to meet the cap, it must be able to cross borders to reach that water—are unpersuasive. Pp. 20–22. 2. The Oklahoma water statutes also do not run afoul of the Commerce Clause. Tarrant claims that the statutes discriminate against interstate commerce by preventing water left unallocated under the Compact from being distributed out of State. But Tarrant’s assumption that some water is left “unallocated” is incorrect. The interpretive comment for Article V of the Compact makes clear that when the flow is above 3,000 CFS, “all states are free to use whatever amount of water they can put to beneficial use,” subject to the requirement that if the amount of available water cannot satisfy all of those uses, “each state will honor the other’s right to 25% of the excess flow.” If more than 25 percent of subbasin 5’s water is located in Oklahoma, that water is not “unallocated”; rather, it is allocated to Oklahoma unless and until another State calls for an accounting and Oklahoma is asked to refrain from utilizing more than its entitled share. Pp. 22–24. 656 F. 3d 1222, affirmed.

(Slip Opinion) OCTOBER TERM, 2012 1
Syllabus
NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
being done in connection with this case, at the time the opinion is issued.
The syllabus constitutes no part of the opinion of the Court but has been
prepared by the Reporter of Decisions for the convenience of the reader.
See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.
SUPREME COURT OF THE UNITED STATES
Syllabus
TARRANT REGIONAL WATER DISTRICT v.
HERRMANN ET AL.
CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
THE TENTH CIRCUIT
No. 11–889. Argued April 23, 2013—Decided June 13, 2013
The Red River Compact (or Compact) is a congressionally sanctioned
agreement that allocates water rights within the Red River basin
among the States of Oklahoma, Texas, Arkansas, and Louisiana.
The area it governs is divided into five separate subdivisions called
“Reaches,” each of which is further divided into smaller “subbasins.”
At issue here are rights under the Compact to water located in Oklahoma’s portion of Reach II, subbasin 5. In Reach II, the Compact—
recognizing that Louisiana lacks suitable reservoir sites to store water during high flow periods and that the upstream States (Texas,
Oklahoma, and Arkansas) were unwilling to release their own stored
water for the benefit of a downstream State—granted control over
the water in four upstream subbasins (subbasins 1 through 4) to the
States in which each subbasin is located and required that water in a
fifth subbasin, subbasin 5, be allowed to flow to Louisiana at certain
minimum levels. Section 5.05(b)(1) of the Compact gives the States
“equal rights” to the use of subbasin 5’s waters when the flow is 3,000
cubic feet per second (CFS) or more, “provided no state is entitled to
more than 25 percent of the water in excess of 3,000 [CFS].” Under
the Compact, States are also entitled to continue with their intrastate water administration.
Petitioner Tarrant Regional Water District (Tarrant) is a Texas
state agency responsible for providing water to north-central Texas
and its rapidly growing population. After unsuccessfully attempting
to purchase water from Oklahoma and others, Tarrant sought a water resource permit from the Oklahoma Water Resources Board
(OWRB), respondents here, to take surface water from a tributary of
the Red River at a point located in Oklahoma’s portion of subbasin 5 2 TARRANT REGIONAL WATER DIST. v. HERRMANN
Syllabus
of Reach II. Knowing that the OWRB would likely deny its permit
application because of Oklahoma water laws that effectively prevent
out-of-state applicants from taking or diverting water from within
Oklahoma’s borders, Tarrant filed suit in federal court simultaneously with its permit application, seeking to enjoin the OWRB’s enforcement of the state statutes on grounds that they were pre-empted by
federal law in the form of the Compact and violated the Commerce
Clause by discriminating against interstate commerce in water. The
District Court granted summary judgment for the OWRB, and the
Tenth Circuit affirmed.
Held:
1. The Compact does not pre-empt the Oklahoma water statutes.
Pp. 9–22.
(a) Tarrant claims that §5.05(b)(1) creates a borderless common
in subbasin 5 in which each of the signatory States may cross each
other’s boundaries to access a shared pool of water. Tarrant observes
that §5.05(b)(1)’s “equal rights” language grants each State an equal
entitlement to subbasin 5’s waters, subject to a 25 percent cap, and
argues that its silence concerning state lines indicates that the Compact’s drafters did not intend the provision to allocate water according to state borders. The OWRB counters that §5.05(b)(1)’s “equal
rights” afford each State an equal opportunity to use subbasin 5’s excess water within each State’s own borders, but that its silence on
cross-border rights indicates that the Compact’s drafters had no intention to create any such rights in the signatory States. Pp. 9–11.
(b) Because interstate compacts are construed under contractlaw principles, see Texas v. New Mexico, 482 U. S. 124, 128, the Court
begins by examining the Compact’s express terms as the best indication of the parties’ intent. However, §5.05(b)(1)’s silence is, at the
very least, ambiguous regarding cross-border rights under the Compact, so the Court turns to other interpretive tools to shed light on
the drafters’ intent. Three things persuade the Court that the Compact did not grant cross-border rights: the well-established principle
that States do not easily cede their sovereign powers; the fact that
other interstate water compacts have treated cross-border rights explicitly; and the parties’ course of dealing. Pp. 11–22.
(1) The sovereign States possess an “absolute right to all their
navigable waters and the soils under them for their own common
use.” Martin v. Lessee of Waddell, 16 Pet. 367, 410. So, for example,
“ ‘[a] court deciding a question of title to [a] bed of navigable water
[within a State’s boundaries] must . . . begin with a strong presumption’ against defeat of a State’s title.” United States v. Alaska, 521
U. S. 1, 34. It follows, then, that “[i]f any inference at all is to be
drawn from” silence in compacts touching on the States’ authority to Cite as: 569 U. S. ____ (2013) 3
Syllabus
control their waters, “it is that each State was left to regulate the activities of her own citizens.” Virginia v. Maryland, 540 U. S. 56, 67.
Tarrant contends that §5.05(b)(1)’s silence infers that the signatory
States dispensed with the core state prerogative to control water
within its borders. But since States rarely relinquish their sovereign
powers, the better understanding is that there would be a clear indication of such devolution, not inscrutable silence. Tarrant counters
that its interpretation would not intrude on any sovereign prerogative of Oklahoma, which would retain its authority to regulate the
water within its borders. But adopting Tarrant’s reading would necessarily entail assuming that Oklahoma and three other States silently surrendered substantial control over their waters when they
agreed to the Compact. Pp. 14–16.
(2) Looking to the customary practices employed in other interstate compacts also helps in ascertaining the parties’ intent. See,
e.g., Alabama v. North Carolina, 560 U. S. 330, ___. Many compacts
feature unambiguous language permitting signatory States to cross
each other’s borders to fulfill obligations under the compacts, and
many provide for the terms and mechanics of how such relationships
will operate. The absence of comparable provisions in the Red River
Compact strongly suggests that cross-border rights were never intended to be part of the agreement. Tarrant claims that not all interstate compacts have such explicit language, but cites only one such
compact, and even it sets out a detailed scheme that would apply to
any contemplated diversions. Similarly, even if §2.05(d) of the Compact, which gives “[e]ach Signatory State . . . the right to” “[u]se the
bed and banks of the Red River and its tributaries to convey stored
water, imported or exported water, and water apportioned according
to this Compact,” is read to establish cross-border diversions, it does
so through express language, not through an inference from silence.
Pp. 16–20.
(3) The parties’ conduct under the Compact also undermines
Tarrant’s position. See Alabama v. North Carolina, 560 U. S., at ___.
Once the Compact was approved in 1980, no signatory State pressed
for a cross-border diversion until Tarrant filed suit in 2007. And Tarrant’s earlier offer to purchase water from Oklahoma was a strange
decision if Tarrant believed the Compact entitled it to demand water
without payment. Nor is there any indication that Tarrant, any other Texas agency, or Texas itself previously made any mention of
cross-border rights within the Compact; and none of the other signatory States has ever made such a claim. P. 20.
 (4) Tarrant’s remaining arguments—that its interpretation is
necessary to realize the “structure and purpose of Reach II”; and that
§5.05(b)(1)’s 25 percent cap on each State’s access to subbasin 5’s ex-4 TARRANT REGIONAL WATER DIST. v. HERRMANN
Syllabus
cess water implies that if a State cannot access sufficient water within its borders to meet the cap, it must be able to cross borders to
reach that water—are unpersuasive. Pp. 20–22.
2. The Oklahoma water statutes also do not run afoul of the Commerce Clause. Tarrant claims that the statutes discriminate against
interstate commerce by preventing water left unallocated under the
Compact from being distributed out of State. But Tarrant’s assumption that some water is left “unallocated” is incorrect. The interpretive comment for Article V of the Compact makes clear that when the
flow is above 3,000 CFS, “all states are free to use whatever amount
of water they can put to beneficial use,” subject to the requirement
that if the amount of available water cannot satisfy all of those uses,
“each state will honor the other’s right to 25% of the excess flow.” If
more than 25 percent of subbasin 5’s water is located in Oklahoma,
that water is not “unallocated”; rather, it is allocated to Oklahoma
unless and until another State calls for an accounting and Oklahoma
is asked to refrain from utilizing more than its entitled share.
Pp. 22–24.
656 F. 3d 1222, affirmed.
SOTOMAYOR, J., delivered the opinion for a unanimous Court. _________________
_________________
Cite as: 569 U. S. ____ (2013) 1
Opinion of the Court
NOTICE: This opinion is subject to formal revision before publication in the
preliminary print of the United States Reports. Readers are requested to
notify the Reporter of Decisions, Supreme Court of the United States, Washington, D. C. 20543, of any typographical or other formal errors, in order
that corrections may be made before the preliminary print goes to press.
SUPREME COURT OF THE UNITED STATES
No. 11–889
TARRANT REGIONAL WATER DISTRICT,
PETITIONER v. RUDOLF JOHN
HERRMANN ET AL.
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE TENTH CIRCUIT
[June 13, 2013]
JUSTICE SOTOMAYOR delivered the opinion of the Court.
The Red River Compact, (or Compact), 94 Stat. 3305,
allocates water rights among the States within the Red
River basin as it winds through Texas, Oklahoma, Arkansas, and Louisiana. Petitioner Tarrant Regional Water
District (Tarrant), a Texas agency, claims that it is entitled to acquire water under the Compact from within
Oklahoma and that therefore the Compact pre-empts
several Oklahoma statutes that restrict out-of-state diversions of water. In the alternative, Tarrant argues that the
Oklahoma laws are unconstitutional restrictions on interstate commerce. We hold that Tarrant’s claims lack merit.
I
A
The Red River (or River) begins in the Llano Estacado
Mesa on the border between New Mexico and Texas.
From this broad plain, it first runs through the Texas
Panhandle and then marks the border between Texas and
Oklahoma. It continues in an easterly direction until it
reaches the shared border with Arkansas. Once the River 2 TARRANT REGIONAL WATER DIST. v. HERRMANN
Opinion of the Court
enters Arkansas, it turns southward and flows into Louisiana, where it empties into the Mississippi and Atchafalaya Rivers.
As an important geographic feature of this region, the
Red River has lent its name to a valley, a Civil War campaign, and a famed college football rivalry between the
Longhorns of Texas and the Sooners of Oklahoma. But
college pride has not been the only source of controversy
between Texas and Oklahoma regarding the Red River.
The River has been the cause of numerous historical conflicts between the two States, leading to a mobilization of
their militias at one time, Oklahoma v. Texas, 258 U. S.
574, 580 (1922), and the declaration of martial law along a
stretch of the River by Oklahoma Governor “Alfalfa Bill”
Murray at another, see Okla. H. Res. 1121, 50th Legislature, 2d Sess. (2006) (resolution commemorating “Alfalfa
Bill” Murray’s actions during the “Red River Bridge War”).
Such disputes over the River and its waters are a natural
result of the River’s distribution of water flows. The River’s course means that upstream States like Oklahoma
and Texas may appropriate substantial amounts of water
from both the River and its tributaries to the disadvantage
of downstream States like Arkansas and especially Louisiana, which lacks sufficiently large reservoirs to store
water.
Absent an agreement among the States, disputes over
the allocation of water are subject to equitable apportionment by the courts, Arizona v. California, 460 U. S. 605,
609 (1983), which often results in protracted and costly
legal proceedings. Thus in 1955, to forestall future disputes over the River and its water, Congress authorized
the States of Arkansas, Louisiana, Oklahoma, and Texas
to negotiate a compact to apportion the water of the Red
River basin among themselves. See Act of Aug. 11, 1955,
Pub. L. 346, 69 Stat. 654. These negotiations lasted over
20 years and finally culminated in the signing of the Red Cite as: 569 U. S. ____ (2013) 3
Opinion of the Court
River Compact in 1978. Congress approved the Compact
in 1980, transforming it into federal law. See Act of Dec.
22, 1980, 94 Stat. 3305; Compact, 1 App. 7–51.
One of the Compact’s principal purposes was “[t]o provide an equitable apportionment among the Signatory
States of the water of the Red River and its tributaries.”
§1.01(b), id., at 9. The Compact governs the allocation of
water along the Red River and its tributaries from the
New Mexico and Texas border to its terminus in Louisiana. §§2.12(a)–(e), id., at 13. This stretch is divided into
five separate subdivisions called “Reach[es],” ibid., each of
which is further divided into smaller “subbasins,” see, e.g.,
§§5.01–5.05, id., at 22–26 (describing subbasins 1 through
5 of Reach II). (See Appendix A, infra, for a map.)
At issue in this case are rights under the Compact to
water located in Oklahoma’s portion of subbasin 5 of
Reach II, which occupies “that portion of the Red River,
together with its tributaries, from Denison Dam down to
the Arkansas-Louisiana state boundary, excluding all
tributaries included in the other four subbasins of Reach
II.” §5.05(a), 1 App. 24–25. (See Appendix B, infra, for a
map.) The Compact’s interpretive comments1
 explain that
during negotiations, Reach II posed the greatest difficulty
to the parties’ efforts to reach agreement. Comment on
Art. V, 1 App. 27. The problem was that Louisiana, the
farthest downstream State, lacks suitable reservoir sites
and therefore cannot store water during high flow periods
to meet its future needs. The upstream States (Texas,
Oklahoma, and Arkansas), which control the River’s flow,
were unwilling to release water stored within their own
reservoirs for the benefit of any downstream States, like
——————
1
Interpretive comments were included in the Compact so that future
readers “might be apprised of the intent of the Compact Negotiation
Committee with regard to each Article of the Compact.” Compact,
Comment on Preamble, 1 App. 9. 4 TARRANT REGIONAL WATER DIST. v. HERRMANN
Opinion of the Court
Louisiana. Without any such release, there would be no
guaranteed flow of water to Louisiana.
The provisions of the Compact relating to Reach II were
crafted to address this problem. To this end, Reach II was
divided into five subbasins. The upstream subbasins,
numbered 1 through 4, were drawn to end at “existing,
authorized or proposed last downstream major damsites,”
see, e.g., §5.01(a), id., at 22, on the tributaries leading to
the Red River before reaching the main stem of the River.
These dams allow the parties managing them to control
water along the tributaries before it travels farther downstream and joins the flow of the main stem of the River.
For the most part, the Compact granted control over the
water in these subbasins to the States in which each
subbasin is located.2
 The remaining subbasin, subbasin 5,
instead requires that water be allowed to flow to Louisiana through the main stem of the River at certain minimum levels, assuring Louisiana an allocation of the River’s
waters and solving its flowthrough problem.
The provision of the Compact central to the present
dispute is §5.05(b)(1), which sets the following allocation
during times of normal flow:
“(1) The Signatory States shall have equal rights to
the use of runoff originating in subbasin 5 and un-
——————
2
Within subbasins 1, 2, and 4, water was fully apportioned to a single
State. See Compact §5.01(b), id., at 22–23 (apportioning water of
subbasin 1 and its “unrestricted use” to Oklahoma); §5.02(b), id., at 23
(same for Texas with respect to subbasin 2); §5.04(b), id., at 24 (same
for Texas with respect to subbasin 4). Only subbasin 3, which includes
portions of Oklahoma and Arkansas, breaks from this pattern and was
divided along the lines of a 60-to-40 split, with both States having “free
and unrestricted use of the water of this subbasin within their respective states, subject, however, to the limitation that Oklahoma shall
allow a quantity of water equal to the 40 percent of the total runoff
originating below the following existing, authorized or proposed last
major downstream damsites in Oklahoma to flow into Arkansas.”
§5.03(b), id., at 23–24. Cite as: 569 U. S. ____ (2013) 5
Opinion of the Court
designated water flowing into subbasin 5, so long as
the flow of the Red River at the Arkansas-Louisiana
state boundary is 3,000 cubic feet per second [hereinafter CFS] or more, provided no state is entitled to
more than 25 percent of the water in excess of 3,000
[CFS].”3 Id., at 25.
In these normal circumstances (i.e., when flows at the
Arkansas-Louisiana border are above 3,000 CFS), this
provision and its interpretive comment make clear that
“all states are free to use whatever amount of water they
can put to beneficial use.” Comment on Art. V, id., at 30.
But if the amount of water above 3,000 CFS cannot satisfy
all such uses, then “each state will honor the other’s right
to 25% of the excess flow.” Ibid. However, when the flow
of the River diminishes at the Arkansas-Louisiana border,
the upstream States must permit more water to reach
Louisiana.4
 Subbasin 5’s allocation scheme allows up-
——————
3
The Compact defines “undesignated water” as “all water released
from storage other than ‘designated water.’ ” §3.01(l), id., at 17.
“[D]esignated water” means “water released from storage, paid for by
non-Federal interests, for delivery to a specific point of use or diversion.” §3.01(k), ibid.
4
In such circumstances, the two relevant paragraphs provide:
“(2) Whenever the flow of the Red River at the Arkansas-Louisiana
state boundary is less than 3,000 [CFS], but more than 1,000 [CFS],
the States of Arkansas, Oklahoma, and Texas shall allow to flow into the
Red River for delivery to the State of Louisiana a quantity of water
equal to 40 percent of the total weekly runoff originating in subbasin
5 and 40 percent of undesignated water flowing into subbasin 5; provided, however, that this requirement shall not be interpreted to require
any state to release stored water.
“(3) Whenever the flow of the Red River at the Arkansas-Louisiana
state boundary falls below 1,000 [CFS], the States of Arkansas, Oklahoma, and Texas shall allow a quantity of water equal to all the weekly
runoff originating in subbasin 5 and all undesignated water flowing in
subbasin 5 within their respective states to flow into the Red River as
required to maintain a 1,000 [CFS] flow at the Arkansas-Louisiana
state boundary.” §5.05(b), id., at 25. 6 TARRANT REGIONAL WATER DIST. v. HERRMANN
Opinion of the Court
stream States to keep the water that they have stored, but
also ensures that Louisiana will receive a steady supply of
water from the Red River, with each upstream State
contributing during times of low flow.
To ensure that its apportionments are honored, the
Compact includes an accounting provision, but an accounting is not mandatory “until one or more affected states
deem the accounting necessary.” §2.11, id., at 13; see
Comment on Art. II, id., at 15–16. This is because the
“extensive gaging and record keeping required” to carry
out such an accounting would impose “a significant financial burden on the involved states.” Id., at 16. Given
these costs, the signatory States did “not envisio[n] that it
w[ould] be undertaken as a routine matter.” Ibid. Indeed,
it appears that no State has ever asked for such an accounting in the Compact’s history. See Brief for Respondents 45; Reply Brief 11–12.
While the Compact allocates water rights among its
signatories, it also provides that it should not “be deemed
to . . . [i]nterfere with or impair the right or power of any
Signatory State to regulate within its boundaries the
appropriation, use, and control of water, or quality of
water, not inconsistent with its obligations under this
Compact.” §2.10, 1 App. 12. Rather, “[s]ubject to the
general constraints of water availability and the apportionment of the Compact, each state [remains] free to
continue its existing internal water administration.”
Comment on Art. II, id., at 14. Even during periods of
water shortage, “no attempt is made to specify the steps
that will be taken [by States to ensure water deliveries]; it
is left to the state’s internal water administration.” Ibid.
B
In the years since the Red River Compact was ratified
by Congress, the region’s population has increased dramatically. In particular, the population of the Dallas-Fort Cite as: 569 U. S. ____ (2013) 7
Opinion of the Court
Worth metropolitan area in north Texas has grown from
roughly 5.1 million inhabitants in 2000 to almost 6.4
million in 2010, a jump of over 23 percent and among the
largest in the United States during this period. See Dept.
of Commerce, Census Bureau, P. Mackun & S. Wilson,
Population Distribution and Change: 2000 to 2010 (Mar.
2011). This growth has strained regional water supplies,
and north Texas’ need for water has been exacerbated in
recent years by a long and costly drought. See generally
Galbraith, A Drought More Than Texas-Size, International
Herald Tribune, Oct. 3, 2011, p. 4.
Against this backdrop, petitioner Tarrant, a Texas state
agency responsible for providing water to north-central
Texas (including the cities of Fort Worth, Arlington, and
Mansfield), has endeavored to secure new sources of water
for the area it serves. From 2000 to 2002, Tarrant, along
with several other Texas water districts, offered to purchase water from Oklahoma and the Choctaw and Chickasaw Nations. See 2 App. 336–382. But these negotiations
were unsuccessful and Tarrant eventually abandoned
these efforts.
Because Texas’ need for water only continued to grow,
Tarrant settled on a new course of action. In 2007, Tarrant sought a water resource permit from the Oklahoma
Water Resources Board (OWRB),5
 respondents here, to
take 310,000 acre feet6
 per year of surface water from the
——————
5
Under §2.10 of the Compact each signatory State retains “the right
or power . . . to regulate within its boundaries the appropriation, use,
and control of water.” Id., at 12. Thus, the Compact does not expressly
pre-empt any state laws that address the control of water. Oklahoma
law, in turn, requires that any “state or federal governmental agency”
that “intend[s] to acquire the right to the beneficial use of any water” in
Oklahoma must apply to the OWRB for “a permit to appropriate” water
before “commencing any construction” or “taking [any water] from any
constructed works.” Okla. Stat., Tit. 82, §105.9 (West 2013).
6
An acre-foot is equivalent to the volume of one acre of surface area
filled to a depth of one foot. Webster’s Third New International Dic-8 TARRANT REGIONAL WATER DIST. v. HERRMANN
Opinion of the Court
Kiamichi River, a tributary of the Red River located in
Oklahoma. Tarrant proposed to divert the Kiamichi River,
at a point located in subbasin 5 of Reach II, before it discharges into the Red River and, according to Tarrant, becomes too saline for potable use.
Tarrant knew, however, that Oklahoma would likely
deny its permits because various state laws (collectively,
the Oklahoma water statutes) effectively prevent out-ofstate applicants from taking or diverting water from within
Oklahoma’s borders. These statutes include a requirement that the OWRB consider, when evaluating an application to take water out of State, whether that water
“could feasibly be transported to alleviate water shortages in the State of Oklahoma.” Okla. Stat., Tit. 82,
§105.12(A)(5) (West 2013). The statutes also require that
no permit issued by the OWRB to use water outside of the
State shall “[i]mpair the ability of the State of Oklahoma
to meet its obligations under any interstate stream compact.” §105.12A(B)(1). A separate provision creates a
permitting review process that applies only to out-of-
state water users. §105.12(F). Oklahoma also requires
legislative approval for out-of-state water-use permits,
§105.12A(D), and further provides that “[w]ater use within
Oklahoma . . . be developed to the maximum extent feasible for the benefit of Oklahoma so that out-of-state downstream users will not acquire vested rights therein to the
detriment of the citizens of this state,” §1086.1(A)(3).
Interpreting these laws, Oklahoma’s attorney general has
concluded that “we consider the proposition unrealistic
that an out-of-state user is a proper permit applicant
before the [OWRB]” because “[w]e can find no intention to
create the possibility that such a valuable resource as
water may become bound, without compensation, to use by
an out-of-state user.” 1 App. 118.
——————
tionary 19 (1966). Cite as: 569 U. S. ____ (2013) 9
Opinion of the Court
When Tarrant filed its permit application, it also filed
suit against respondents in Federal District Court. As
relevant here, Tarrant sought to enjoin enforcement of the
Oklahoma water statutes by the OWRB. Tarrant argued
that the statutes, and the interpretation of them adopted
by Oklahoma’s attorney general, were pre-empted by
federal law and violated the Commerce Clause by discriminating against interstate commerce in water.
The District Court granted summary judgment for the
OWRB on both of Tarrant’s claims. See No. CIV–07–
0045–HE, 2010 WL 2817220, *4 (WD Okla., July 16,
2010); No. CIV–07–0045–HE (WD Okla., Nov. 18, 2009),
App. to Pet. for Cert. 72a–73a, 2009 WL 3922803, *8. The
Tenth Circuit affirmed. 656 F. 3d 1222, 1250 (2011).7
We granted Tarrant’s petition for a writ of certiorari,
568 U. S. ___ (2013), and now affirm the judgment of the
Tenth Circuit.
II
A
Tarrant claims that under §5.05(b)(1) of the Compact, it
has the right to cross state lines and divert water from
Oklahoma located in subbasin 5 of Reach II and that the
Oklahoma water statutes interfere with its ability to
exercise that right. Section 5.05(b)(1) provides:
“The Signatory States shall have equal rights to the
use of runoff originating in subbasin 5 and undesignated water following into subbasin 5, so long as the
flow of the Red River at the Arkansas-Louisiana state
boundary is 3,000 [CFS] or more, provided no state is
entitled to more than 25 percent of the water in excess
of 3,000 [CFS].” 1 App. 25.
——————
7
The parties have stipulated that OWRB will not take action on
Tarrant’s application until this litigation has concluded. Brief for Petitioner 16. 10 TARRANT REGIONAL WATER DIST. v. HERRMANN
Opinion of the Court
In Tarrant’s view, this provision essentially creates a
borderless common in which each of the four signatory
States may cross each other’s boundaries to access a
shared pool of water. Tarrant reaches this interpretation
in two steps. First, it observes that §5.05(b)(1)’s “equal
rights” language grants each State an equal entitlement to
the waters of subbasin 5, subject to a 25 percent cap.
Second, Tarrant argues §5.05(b)(1)’s silence concerning
state lines indicates that the Compact’s drafters did not
intend to allocate water according to state borders in this
section. According to Tarrant, “the ‘25 percent’ language
[of §5.05(b)(1)] makes clear that, in exercising its ‘equal
rights’ to the common pool of water, no State may take
more than a one-quarter share,” Reply Brief 3, but any of
the signatory States may “cross state lines to obtain [its]
shar[e] of Subbasin 5 waters,” Brief for Petitioner 32.
The OWRB disputes this reading. In its view, the
“equal rights” promised by §5.05(b)(1) afford each State an
equal opportunity to make use of the excess water within
subbasin 5 of Reach II but only within each State’s own
borders. This is because the OWRB reads §5.05(b)(1)’s
silence differently from Tarrant. The OWRB interprets
that provision’s absence of language granting any crossborder rights to indicate that the Compact’s drafters had
no intention to create any such rights in the signatory
States.
Unraveling the meaning of §5.05(b)(1)’s silence with
respect to state lines is the key to resolving whether the
Compact pre-empts the Oklahoma water statutes.8
 If
——————
8
The Compact Clause of the Constitution provides that “[n]o State
shall, without the Consent of Congress, . . . enter into any Agreement or
Compact with another State.” Art. I, §10, cl. 3. Accordingly, before a
compact between two States can be given effect it must be approved by
Congress. See Virginia v. Maryland, 540 U. S. 56, 66 (2003). Once a
compact receives such approval, it is “transform[ed] . . . into a law of
the United States.” Ibid. (internal quotation marks omitted). The Cite as: 569 U. S. ____ (2013) 11
Opinion of the Court
§5.05(b)(1)’s silence means that state borders are irrelevant to the allocation of water in subbasin 5 of Reach II,
then the Oklahoma water laws at issue conflict with the
cross-border rights created by federal law in the form of
the Compact and must be pre-empted. But if §5.05(b)(1)’s
silence instead reflects a background understanding on
the part of the Compact’s drafters that state borders were
to be respected within the Compact’s allocation, then the
Oklahoma statutes do not conflict with the Compact’s
allocation of water.
B
Interstate compacts are construed as contracts under
the principles of contract law. Texas v. New Mexico, 482
U. S. 124, 128 (1987). So, as with any contract, we begin
by examining the express terms of the Compact as the
best indication of the intent of the parties, see also Montana v. Wyoming, 563 U. S. ___, ___, and n. 4, ___, (2011)
(slip op., at 5, and n. 4, 17); Restatement (Second) of Contracts §203(b) (1979).
Tarrant argues that because other provisions of the
Compact reference state borders, §5.05(b)(1)’s silence with
respect to state lines must mean that the Compact’s drafters intended to permit cross-border diversions. For example, §5.03(b), which governs subbasin 3 of Reach II,
provides that
“[t]he States of Oklahoma and Arkansas shall have
free and unrestricted use of the water of this subbasin
within their respective states, subject, however, to the
limitation that Oklahoma shall allow a quantity of
water equal to . . . 40 percent of the total runoff origi-
——————
Supremacy Clause, Art. VI, cl. 2, then ensures that a congressionally
approved compact, as a federal law, pre-empts any state law that
conflicts with the Compact. See Fidelity Fed. Sav. & Loan Assn. v. De
la Cuesta, 458 U. S. 141, 152–153 (1982). 12 TARRANT REGIONAL WATER DIST. v. HERRMANN
Opinion of the Court
nating below the following existing, authorized or
proposed last major downstream damsites in Okla-
homa to flow into Arkansas.” 1 App. 23–24 (emphasis
added).
Section 6.03(b), which covers subbasin 3 of Reach III,
similarly provides that “Texas and Louisiana within their
respective boundaries shall each have the unrestricted use
of the water of this subbasin subject to the following
[conditions].” Id., at 33 (emphasis added). Thus, §5.03(b)
and §6.03(b) mimic §5.05(b)(1) in allocating water rights
within a subbasin, but differ in that they make explicit reference to water use “within” state boundaries. Relying on
the expressio unius canon of construction, Tarrant finds
that §5.05(b)’s silence regarding borders is significant
because “‘[w]here Congress includes particular language
in one section of a statute but omits it in another section of
the same Act, it is generally presumed [that] Congress
acts intentionally and purposely in the disparate inclusion
or exclusion.’” Brief for Petitioner 29 (quoting Russello v.
United States, 464 U. S. 16, 23 (1983)).
But Tarrant’s argument fails to account for other sections of the Compact that cut against its reading. For
example, §5.05(b)(3), which governs the waters of subbasin
5 in Reach II when flows are below 1,000 CFS, requires
that during such periods, Arkansas, Texas, and Oklahoma
allow water “within their respective states to flow into the
Red River as required to maintain a 1,000 [CFS] flow at
the Arkansas-Louisiana state boundary.” 1 App. 25 (emphasis added). Obviously none of the upstream States can
redirect water that lies outside of their borders, so the
phrase “within their respective states” is superfluous in
§5.05(b)(3). In contrast, §5.05(b)(2), which governs when
the River’s flow at the Arkansas-Louisiana border is above
1,000 CFS but below 3,000 CFS, requires that upstream
States allow a flow to Louisiana equivalent to 40 percent Cite as: 569 U. S. ____ (2013) 13
Opinion of the Court
of total weekly runoff originating within the subbasin and
40 percent of undesignated water flowing into subbasin 5
of Reach II. Id., at 25. This language can only refer to
water within each State’s borders because otherwise each
State would have to contribute 40 percent to the total
water flow, which would add up to more than 100 percent.
Read together and to avoid absurd results, §§5.05(b)(2)
and (3) suggest that each upstream State is individually
responsible for ensuring that sufficient subbasin 5 water
located within its respective borders flows down to Louisiana, even though §5.05(b)(2) lacks any explicit reference to
state lines.
Applying Tarrant’s understanding of §5.05(b)(1)’s silence regarding state lines to other of the Compact’s provisions would produce further anomalous results. Consider
§6.01(b). That provision states that “Texas is apportioned
sixty (60) percent of the runoff of [subbasin 1 of Reach III]
and shall have unrestricted use thereof; Arkansas is entitled to forty (40) percent of the runoff of this subbasin.”
Id., at 32. Because Texas is upstream from Arkansas,
water flows from Texas to Arkansas. Given this situation,
the commonsense reason for §6.01(b)’s 60-to-40 allocation
is to prevent Texas from barring the flow of water to Arkansas. While there is no reference to state boundaries in
the section’s text, the unstated assumption underlying this
provision is that Arkansas must wait for its 40 percent
share to go through Texas before it can claim it. But
applying Tarrant’s understanding of silence regarding
state borders to this section would imply that Arkansas
could enter into Texas without having to wait for the
water that will inevitably reach it. This counterintuitive
outcome would thwart the self-evident purposes of the
Compact. Further, other provisions of the Compact share
this structure of allocating a proportion of water that will 14 TARRANT REGIONAL WATER DIST. v. HERRMANN
Opinion of the Court
flow from an upstream State to a downstream one.9
 Accepting Tarrant’s reading would upset the balance struck
by all these sections.
At the very least, the problems that arise from Tarrant’s
proposed reading suggest that §5.05(b)(1)’s silence is
ambiguous regarding cross-border rights under the Compact. We therefore turn to other interpretive tools to shed
light on the intent of the Compact’s drafters. See Oklahoma v. New Mexico, 501 U. S. 221, 235, n. 5 (1991).10
Three things persuade us that cross-border rights were
not granted by the Compact: the well-established principle
that States do not easily cede their sovereign powers,
including their control over waters within their own territories; the fact that other interstate water compacts have
treated cross-border rights explicitly; and the parties’
course of dealing.
1
The background notion that a State does not easily cede
its sovereignty has informed our interpretation of interstate compacts. We have long understood that as sovereign entities in our federal system, the States possess an
——————
9
See Compact §4.01(b), 1 App. 18 (“The annual flow within this subbasin is hereby apportioned sixty (60) percent to Texas and forty (40)
percent to Oklahoma”); §6.02(b), id., at 32 (“Arkansas is apportioned
sixty (60) percent of the runoff of this subbasin and shall have unrestricted use thereof; Louisiana is entitled to forty (40) percent of the
runoff of this subbasin”).
10There is, however, one interpretive tool that is inapplicable here:
the presumption against pre-emption. The Court of Appeals repeatedly
referenced and relied upon the presumption in its opinion. See 656
F. 3d 1222, 1239, 1242, 1245–1246 (CA10 2011). Yet the presumption
against pre-emption is rooted in “respect for the States as ‘independent
sovereigns in our federal system’ ” and “assume[s] that ‘Congress does
not cavalierly pre-empt’ ” state laws. Wyeth v. Levine, 555 U. S. 555,
565–566, n. 3 (2009). When the States themselves have drafted and
agreed to the terms of a compact, and Congress’ role is limited to
approving that compact, there is no reason to invoke the presumption. Cite as: 569 U. S. ____ (2013) 15
Opinion of the Court
“absolute right to all their navigable waters and the soils
under them for their own common use.” Martin v. Lessee
of Waddell, 16 Pet. 367, 410 (1842). Drawing on this
principle, we have held that ownership of submerged
lands, and the accompanying power to control navigation,
fishing, and other public uses of water, “is an essential attribute of sovereignty,” United States v. Alaska,
521 U. S. 1, 5 (1997). Consequently, “‘[a] court deciding
a question of title to [a] bed of navigable water [within a
State’s boundaries] must . . . begin with a strong presumption’ against defeat of a State’s title.” Id., at 34 (quoting
Montana v. United States, 450 U. S. 544, 552 (1981)). See
also Solid Waste Agency of Northern Cook Cty. v. Army
Corps of Engineers, 531 U. S. 159, 174 (2001); Utah Div. of
State Lands v. United States, 482 U. S. 193, 195 (1987).
Given these principles, when confronted with silence in
compacts touching on the States’ authority to control their
waters, we have concluded that “[i]f any inference at all is
to be drawn from [such] silence on the subject of regula-
tory authority, we think it is that each State was left to
regulate the activities of her own citizens.” Virginia v.
Maryland, 540 U. S. 56, 67 (2003). Cf. New Jersey v. New
York, 523 U. S. 767, 783, n. 6 (1998) (“[T]he silence of
the Compact was on the subject of settled law governing
avulsion, which the parties’ silence showed no intent to
modify”).
Tarrant asks us to infer from §5.05(b)(1)’s silence regarding state borders that the signatory States have
dispensed with the core state prerogative to control water
within their own boundaries.11 But as the above demon-
——————
11Of course, the power of States to control water within their borders
may be subject to limits in certain circumstances. For example, those
imposed by the Commerce Clause. See Sporhase v. Nebraska ex rel.
Douglas, 458 U. S. 941, 954–958 (1982). Here we deal only with
whether the parties’ silence on state boundaries in the allocation of
water under a compact suggests that borders are irrelevant for that 16 TARRANT REGIONAL WATER DIST. v. HERRMANN
Opinion of the Court
strates, States rarely relinquish their sovereign powers, so
when they do we would expect a clear indication of such
devolution, not inscrutable silence. We think that the
better understanding of §5.05(b)(1)’s silence is that the
parties drafted the Compact with this legal background in
mind, and therefore did not intend to grant each other
cross-border rights under the Compact.
In response, Tarrant contends that its interpretation
would not intrude on any sovereign prerogative of Oklahoma because that State would retain its authority to
regulate the water within its borders. Because anyone
seeking water from Oklahoma would still have to apply to
the OWRB, receive a permit, and abide by its conditions,
Tarrant argues that Oklahoma’s sovereign authority
remains untouched by its interpretation. But Tarrant
cannot have it both ways. Adopting Tarrant’s reading
would necessarily entail assuming that Oklahoma and
three other States silently surrendered substantial control
over the water within their borders when they agreed to
the Compact. Given the background principles we have
described above, we find this unlikely to have been the
intent of the Compact’s signatories.
2
Looking to the customary practices employed in other
interstate compacts also helps us to ascertain the intent of
the parties to this Compact. See Alabama v. North Carolina,
560 U. S. 330 ___, ___ (2010) (slip op., at 9); Oklahoma,
501 U. S., at 235, n. 5; Texas v. New Mexico, 462 U. S.
554, 565 (1983). See also Restatement (Second) of Contracts §203(b) (explaining that “usage of trade” may be
relevant in interpreting a contract). Many of these other
compacts feature language that unambiguously permits
——————
allocation. As noted infra, at 23–24, Tarrant has not raised any Commerce Clause challenge to Oklahoma’s control of the water allocated to
it by the Compact. Cite as: 569 U. S. ____ (2013) 17
Opinion of the Court
signatory States to cross each other’s borders to fulfill
obligations under the compacts. See, e.g., Amended Bear
River Compact, Art. VIII(A), 94 Stat. 12 (“[N]o State shall
deny the right of another signatory State . . . to acquire
rights to the use of water . . . in one State for use of water
in another”).12 The absence of comparable language in the
Red River Compact counts heavily against Tarrant’s reading of it.
Tellingly, many of these compacts provide for the terms
and mechanics of how such cross-border relationships will
operate, including who can assert such cross-border rights,
see, e.g., Kansas-Nebraska Big Blue River Compact, Art.
VII(1), 86 Stat. 198, who should bear the costs of any
cross-border diversions, see, e.g., Belle Fourche River
Compact, Art. VI, 58 Stat. 96–97, and how such diversions
should be administered, Arkansas River Basin Compact,
Kansas-Oklahoma, Art. VII(A), 80 Stat. 1411. See also
Brief for Professors of Law and Political Science as Amici
Curiae 11–14 (giving more examples).
Provisions like these are critical for managing the complexities that ensue from cross-border diversions. Consider
the mechanics of a cross-border diversion or taking of
water in this case. If Tarrant were correct, then appli-
——————
12See also Amended Costilla Creek Compact, Art. III(2), 77 Stat. 353
(“Each State grants for the benefit of the other . . . the rights . . . in one
State for use in the other”); Klamath River Basin Compact, Art. V(A),
71 Stat. 500 (“Each state hereby grants for the benefit of the other . . .
the right . . . in one state for use in the other”); Snake River Compact,
Art. VIII(A), 64 Stat. 32 (“[N]either State shall deny the right of the
other State to acquire rights to the use of water . . . in one State for use
in the other”); South Platte River Compact, Art. VI(1), 44 Stat. 198
(“Colorado consents that Nebraska and its citizens may . . . divert water
from the South Platte River within Colorado for use in Nebraska”);
Upper Colorado River Basin Compact, Art. IX(a), 63 Stat. 37 (“[N]o
State shall deny the right of another signatory State . . . to acquire
rights to the use of water . . . in an upper signatory State for consumptive use in a lower signatory State”). 18 TARRANT REGIONAL WATER DIST. v. HERRMANN
Opinion of the Court
cants from Arkansas, Texas, and Louisiana could all apply
to the OWRB for permits to take water from Oklahoma.
The OWRB would then be obligated to determine the total
amount of water in Oklahoma beyond the 25 percent cap
created in §5.05(b)(1), given that the Compact would only
obligate Oklahoma to deliver water beyond its quarter
share. This alone would be a herculean task because the
Compact does not require ongoing monitoring or accounting, see Compact §2.11, 1 App. 13, and not all of the water
in subbasin 5 is located or originates in Oklahoma. Moreover, the OWRB would be tasked with determining the
priority under the Compact of applicants from other
States. This would almost certainly require the OWRB to
not only determine whether Oklahoma had received more
or less than its 25 percent allotment, but whether other
States had as well. Put plainly, the end result would be
a jurisdictional and administrative quagmire. The provisions in the other interstate water compacts resolve
these complications. The absence of comparable provisions
in the Red River Compact strongly suggests that crossborder rights were never intended to be part of the States’
agreement.
Tarrant counters that not all interstate compacts that
permit cross-border diversions have explicit language to
this effect. On this front, Tarrant manages to identify one
interstate compact that it contends permits cross-border
diversions without express language to that effect, the
Upper Niobrara River Compact, Pub. L. 91–52, 83 Stat.
86. Tarrant observes that this compact, which deals with
a river mostly located in Nebraska with only a small
portion in Wyoming, provides that “[t]here shall be no
restrictions on the use of the surface waters of [the river]
by Wyoming.” See Art. V(A)1, id., at 88. Tarrant suggests
that this language, coupled with the fact that the bulk of
the river is in Nebraska, implicitly indicates that the
compact grants Wyoming a right to enter Nebraska and Cite as: 569 U. S. ____ (2013) 19
Opinion of the Court
use the river’s water. First, we are not convinced that a
single compact’s failure to reference state borders does
much to detract from the overall custom in this area. See
supra, at 16–18, and n. 12. Second, the Upper Niobrara
River Compact is not a helpful counterexample for Tarrant. The general provision that Tarrant quotes is paired
with a host of detailed conditions. See Arts. V(A)1(a)–(f),
83 Stat. 88. Contrary to Tarrant’s position, then, assuming that the Upper Niobrara River compact does create
any cross-border rights, it does so not through silence, but
through the detailed scheme that would apply to any such
contemplated diversions.
Tarrant also argues that §2.05(d) of the Red River Compact, which provides that “[e]ach Signatory State shall
have the right to” “[u]se the bed and banks of the Red
River and its tributaries to convey stored water, imported
or exported water, and water apportioned according to this
Compact,” 1 App. 11, in fact authorizes cross-border diversions. Because the present border between Texas and
Oklahoma east of the Texas Panhandle is set by the vegetation line on the south bank of the River, Red River
Boundary Compact, 114 Stat. 919, Tarrant contends that
§2.05(d) reflects an understanding on the part of the Compact’s drafters that state borders could be crossed. But the
issue is not as simple as Tarrant makes it out to be. When
the Compact was drafted, the Texas-Oklahoma border was
fixed at the south bank of the River. See Texas v. Oklahoma, 457 U. S. 172 (1982). If Texas was able to access
water through the south bank of the River—an issue left
unbriefed by the parties—the Compact’s framers may
have believed that Texas could reach the River and take
water from it without having to enter Oklahoman land,
casting doubt on Tarrant’s theory. In any event, even if
§2.05(d) is read to establish a cross-border right, it does so
through express language setting forth the location and
purposes under which such an incursion is permissible. 20 TARRANT REGIONAL WATER DIST. v. HERRMANN
Opinion of the Court
This is different from the inference from silence that
Tarrant asks us to draw in §5.05(b)(1).
3
The parties’ conduct under the Compact also undermines Tarrant’s position. A “part[y’s] course of performance under the Compact is highly significant” evidence
of its understanding of the compact’s terms. Alabama v.
North Carolina, 560 U. S., at___ (slip op., at 14). Since the
Compact was approved by Congress in 1980, no signatory
State had pressed for a cross-border diversion under the
Compact until Tarrant filed its suit in 2007. Brief for
Respondents 26, 49–51. Indeed, Tarrant attempted to
purchase water from Oklahoma over the course of 2000
until 2002, see supra, at 7, a strange offer if Tarrant believed it was entitled to demand such water without payment under the Compact.
In response, Tarrant maintains that there were “compelling business reasons” for it to purchase water. Reply
Brief 17. We are unpersuaded. If Tarrant believed that it
had a right to water located in Oklahoma, there would
have been “compelling business reasons” to mention this
right given that billions of dollars were at stake. See 2
App. 362–363 (summarizing Texas purchase proposal).
Yet there is no indication that Tarrant or any other Texas
agency or the State of Texas itself previously made any
mention of cross-border rights within the Compact, and
none of the other signatory States has ever made such a
claim.
4
The Compact creates no cross-border rights in Texas.
Tarrant’s remaining arguments do not persuade us
otherwise.
First, Tarrant argues that its interpretation of the
Compact is necessary to realize the “structure and purpose Cite as: 569 U. S. ____ (2013) 21
Opinion of the Court
of Reach II.” Brief for Petitioner 34–38. Tarrant contends
that because the boundary of subbasin 5 is set by the
location of the last existing, authorized, or proposed sites
for a downstream dam before the Red River, see Compact
§§5.01(a), 5.02(a), 5.03(b), 5.04(a), 1 App. 22–24, the Compact allows each of the States upstream from Louisiana to
prevent water from flowing from its tributaries into subbasin 5. Tarrant reasons that each State will therefore
hold whatever water it needs in its upstream basins.
Given this, Tarrant maintains that any water that a State
voluntarily allows to reach subbasin 5 must be surplus
water that State did not intend to use, and if the upstream
State has no need for that water, then there is no reason
not to allow other States to access and use it, even across
borders.
This argument is founded on a shaky premise: It assumes that flows from these dammed-up tributaries are
the sole source of water in subbasin 5. But §5.05(b)(1)
explains that “[s]ignatory States shall have equal rights to
the use of runoff originating in subbasin 5,” as well as
“water flowing into subbasin 5,” which would include flows
from the main stem of the River itself. Id., at 25. Thus,
there are waters that are specific to subbasin 5 separate
from those originating in the tributaries covered by subbasins 1 through 4. Tarrant’s account of the purposes of
subbasin 5 does not explain how these waters were to be
allocated.
Tarrant’s second argument regarding the purposes of
Reach II is that §5.05(b)(1)’s 25 percent cap on each State’s
access to excess water in subbasin 5 should be read to
imply that if a State cannot access sufficient water within
its borders to meet its share under the cap, then it must be
able to cross borders to reach that water. Were it otherwise, Tarrant explains, the 25 percent cap would have no
purpose. To support this argument, Tarrant draws on a
1970 engineering report that it contends shows that only 22 TARRANT REGIONAL WATER DIST. v. HERRMANN
Opinion of the Court
16 percent of the freshwater flowing into subbasin 5 was
located in Texas. Brief for Petitioner 9, n. 5. The OWRB
challenges this percentage with its own calculations
drawn from the report, and asserts that Texas had access
to at least 29 percent of the excess water in subbasin 5
within its own borders. Brief for Respondents 26, 47–48,
and n. 17.
Fortunately, we need not delve into calculations based
on a decades-old engineering report to resolve this argument. As we have explained, supra, at 4–6, Texas does not
have a minimum guarantee of 25 percent of the excess
water in subbasin 5. If it believes that Oklahoma is using
more than its 25 percent allotment and wishes to stop it
from doing so, then it may call for an accounting under
§2.11 of the Compact and, depending on the results of that
accounting, insist that Oklahoma desist from taking more
than its provided share. See Compact §2.11, and Comment on Art. II, 1 App. 13–16. This is the appropriate
remedy provided under the Compact. But Texas has never
done so and Tarrant offers no evidence that in the present
day Texas cannot access its 25 percent share on its own
land.
C
Under the Compact’s terms, water located within Oklahoma’s portion of subbasin 5 of Reach II remains under
Oklahoma’s control. Accordingly, Tarrant’s theory that
Oklahoma’s water statutes are pre-empted because they
prevent Texas from exercising its rights under the Compact must fail for the reason that the Compact does not
create any cross-border rights in signatory States.
III
Tarrant also challenges the constitutionality of the
Oklahoma water statutes under a dormant Commerce
Clause theory. Tarrant argues that the Oklahoma water Cite as: 569 U. S. ____ (2013) 23
Opinion of the Court
statutes impermissibly “‘discriminat[e] against interstate
commerce’ for the ‘forbidden purpose’ of favoring local
interests” by erecting barriers to the distribution of water
left unallocated under the Compact. Brief for Petitioner
47–48 (quoting Department of Revenue of Ky. v. Davis, 553
U. S. 328, 338 (2008)). Tarrant’s argument is premised on
the position that if we “adopt the Tenth Circuit’s or respondent’s interpretation [of the Compact], . . . a substantial amount of Reach II, Subbasin 5 water located in Oklahoma is not apportioned to any State and therefore is
available to permit applicants like Tarrant.” Brief for
Petitioner 47. So, Tarrant continues, because Oklahoma’s
laws prevent this “unallocated water” from being distributed out of State, those laws violate the Commerce Clause.
Tarrant’s assumption that that the Compact leaves
some water “unallocated” is incorrect. The interpretive
comment for Article V of the Compact makes clear that
when the River’s flow is above 3,000 CFS, “all states are
free to use whatever amount of water they can put to
beneficial use,” subject to the requirement that “[i]f the
states have competing uses and the amount of water
available in excess of 3000 CFS cannot satisfy all such
uses, each state will honor the other’s right to 25% of the
excess flow.” 1 App. 29–30. If more than 25 percent of
subbasin 5’s water is located in Oklahoma, that water is
not “unallocated”; rather, it is allocated to Oklahoma
unless and until another State calls for an accounting
and Oklahoma is asked to refrain from utilizing more than
its entitled share.13 The Oklahoma water statutes cannot discriminate against interstate commerce with respect to unallocated waters because the Compact leaves no
——————
13Moreover, even if Oklahoma utilized less than 25 percent of the
excess subbasin 5 water within its territory and allowed the rest to flow
down the River, that water would pass from Reach II into Reach V, see
Compact §2.12, 1 App. 13, the waters of which are completely allocated
to Louisiana, §8.01, id., at 38. Again, no water is left “unallocated.” 24 TARRANT REGIONAL WATER DIST. v. HERRMANN
Opinion of the Court
waters unallocated. Tarrant’s Commerce Clause argument founders on this point.
* * *
The Red River Compact does not pre-empt Oklahoma’s water statutes because the Compact creates no
cross-border rights in its signatories for these statutes to
infringe. Nor do Oklahoma’s laws run afoul of the Commerce Clause. We affirm the judgment of the Court of
Appeals for the Tenth Circuit.
It is so ordered. 

The Port of Los Angeles, a division of the City of Los Angeles, is run by a Board of Harbor Commissioners pursuant to a municipal ordinance known as a tariff. The Port leases marine terminal facilities to operators that load cargo onto and unload it from docking ships. Federally licensed short-haul trucks, called “drayage trucks,” assist in those operations by moving cargo into and out of the Port. In 2007, in response to community concerns over the impact of a proposed port expansion on traffic, the environment, and safety, the Board implemented a Clean Truck Program. As part of that program, the Board devised a standard-form “concession agreement” to govern the relationship between the Port and drayage companies. The agreement requires a company to affix a placard on each truck with a phone number for reporting concerns, and to submit a plan listing off-street parking locations for each truck. Other requirements relate to a company’s financial capacity, its maintenance of trucks, and its employment of drivers. The concession agreement sets out penalties for violations, including possible suspension or revocation of the right to provide drayage services. The Board also amended the Port’s tariff to ensure that every drayage company would enter into the agreement. The amended tariff makes it a misdemeanor, punishable by fine or imprisonment, for a terminal operator to grant access to an unregistered drayage truck. Petitioner American Trucking Associations, Inc. (ATA), whose members include many of the drayage companies at the Port, sued the Port and City, seeking an injunction against the concession agreement’s requirements. ATA principally contended that the requirements are expressly preempted by the Federal Aviation Admin-2 AMERICAN TRUCKING ASSNS., INC. v. LOS ANGELES Syllabus istration Authorization Act of 1994 (FAAAA), see 49 U. S. C. §14501(c)(1). ATA also argued that even if the requirements are valid, Castle v. Hayes Freight Lines, Inc., 348 U. S. 61, prevents the Port from enforcing the requirements by withdrawing a defaulting company’s right to operate at the Port. The District Court held that neither §14501(c)(1) nor Castle prevented the Port from proceeding with its program. The Ninth Circuit mainly affirmed, finding only the driveremployment provision preempted and rejecting petitioner’s Castle claim. Held: 1. The FAAAA expressly preempts the concession agreement’s placard and parking requirements. Section 14501(c)(1) preempts a state “law, regulation, or other provision having the force and effect of law related to a price, route, or service of any motor carrier . . . with respect to the transportation of property.” 49 U. S. C. §14501(c)(1). Because the parties agree that the Port’s placard and parking requirements relate to a motor carrier’s price, route, or service with respect to transporting property, the only disputed question is whether those requirements “hav[e] the force and effect of law.” Section 14501(c)(1) draws a line between a government’s exercise of regulatory authority and its own contract-based participation in a market. The statute’s “force and effect of law” language excludes from the clause’s scope contractual arrangements made by a State when it acts as a market participant, not as a regulator. See, e.g., American Airlines, Inc. v. Wolens, 513 U. S. 219, 229. But here, the Port exercised classic regulatory authority in imposing the placard and parking requirements. It forced terminal operators—and through them, trucking companies—to alter their conduct by implementing a criminal prohibition punishable by imprisonment. That counts as action “having the force and effect of law” if anything does. The Port’s primary argument to the contrary focuses on motives rather than means. But the Port’s proprietary intentions do not control. When the government employs a coercive mechanism, available to no private party, it acts with the force and effect of law, whether or not it does so to turn a profit. Only if it forgoes the (distinctively governmental) exercise of legal authority may it escape §14501(c)(1)’s preemptive scope. That the criminal sanctions fall on terminal operators, not directly on the trucking companies, also makes no difference. See, e.g., Rowe v. New Hampshire Motor Transp. Assn., 552 U. S. 364, 371–373. Pp. 6−10. 2. This Court declines to decide in the case’s present, preenforcement posture whether Castle limits the way the Port can enforce the financial-capacity and truck-maintenance requirements upheld by the Ninth Circuit. Castle rebuffed a State’s attempt to bar a Cite as: 569 U. S. ____ (2013) 3 Syllabus federally licensed motor carrier from its highways for past infringements of state safety regulations. But Castle does not prevent a State from taking off the road a vehicle that is contemporaneously out of compliance with such regulations. And at this juncture, there is no basis for finding that the Port will actually use the concession agreement’s penalty provision as Castle proscribes. Pp. 10−12. 660 F. 3d 384, reversed in part and remanded.

(Slip Opinion) OCTOBER TERM, 2012 1
Syllabus
NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
being done in connection with this case, at the time the opinion is issued.
The syllabus constitutes no part of the opinion of the Court but has been
prepared by the Reporter of Decisions for the convenience of the reader.
See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.
SUPREME COURT OF THE UNITED STATES
Syllabus
AMERICAN TRUCKING ASSOCIATIONS, INC. v. CITY
OF LOS ANGELES, CALIFORNIA, ET AL.
CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
THE NINTH CIRCUIT
No. 11–798. Argued April 16, 2013—Decided June 13, 2013
The Port of Los Angeles, a division of the City of Los Angeles, is run by
a Board of Harbor Commissioners pursuant to a municipal ordinance
known as a tariff. The Port leases marine terminal facilities to operators that load cargo onto and unload it from docking ships. Federally licensed short-haul trucks, called “drayage trucks,” assist in those
operations by moving cargo into and out of the Port. In 2007, in response to community concerns over the impact of a proposed port expansion on traffic, the environment, and safety, the Board implemented a Clean Truck Program. As part of that program, the Board
devised a standard-form “concession agreement” to govern the relationship between the Port and drayage companies. The agreement
requires a company to affix a placard on each truck with a phone
number for reporting concerns, and to submit a plan listing off-street
parking locations for each truck. Other requirements relate to a
company’s financial capacity, its maintenance of trucks, and its employment of drivers. The concession agreement sets out penalties for
violations, including possible suspension or revocation of the right to
provide drayage services. The Board also amended the Port’s tariff to
ensure that every drayage company would enter into the agreement.
The amended tariff makes it a misdemeanor, punishable by fine or
imprisonment, for a terminal operator to grant access to an unregistered drayage truck.
 Petitioner American Trucking Associations, Inc. (ATA), whose
members include many of the drayage companies at the Port, sued
the Port and City, seeking an injunction against the concession
agreement’s requirements. ATA principally contended that the requirements are expressly preempted by the Federal Aviation Admin-2 AMERICAN TRUCKING ASSNS., INC. v. LOS ANGELES
Syllabus
istration Authorization Act of 1994 (FAAAA), see 49 U. S. C.
§14501(c)(1). ATA also argued that even if the requirements are valid, Castle v. Hayes Freight Lines, Inc., 348 U. S. 61, prevents the Port
from enforcing the requirements by withdrawing a defaulting company’s right to operate at the Port. The District Court held that neither
§14501(c)(1) nor Castle prevented the Port from proceeding with its
program. The Ninth Circuit mainly affirmed, finding only the driveremployment provision preempted and rejecting petitioner’s Castle
claim.
Held:
1. The FAAAA expressly preempts the concession agreement’s
placard and parking requirements. Section 14501(c)(1) preempts a
state “law, regulation, or other provision having the force and effect
of law related to a price, route, or service of any motor carrier . . .
with respect to the transportation of property.” 49 U. S. C.
§14501(c)(1). Because the parties agree that the Port’s placard and
parking requirements relate to a motor carrier’s price, route, or service with respect to transporting property, the only disputed question
is whether those requirements “hav[e] the force and effect of law.”
Section 14501(c)(1) draws a line between a government’s exercise of
regulatory authority and its own contract-based participation in a
market. The statute’s “force and effect of law” language excludes
from the clause’s scope contractual arrangements made by a State
when it acts as a market participant, not as a regulator. See, e.g.,
American Airlines, Inc. v. Wolens, 513 U. S. 219, 229. But here, the
Port exercised classic regulatory authority in imposing the placard
and parking requirements. It forced terminal operators—and
through them, trucking companies—to alter their conduct by implementing a criminal prohibition punishable by imprisonment. That
counts as action “having the force and effect of law” if anything does.
The Port’s primary argument to the contrary focuses on motives rather than means. But the Port’s proprietary intentions do not control. When the government employs a coercive mechanism, available
to no private party, it acts with the force and effect of law, whether or
not it does so to turn a profit. Only if it forgoes the (distinctively governmental) exercise of legal authority may it escape §14501(c)(1)’s
preemptive scope. That the criminal sanctions fall on terminal operators, not directly on the trucking companies, also makes no difference. See, e.g., Rowe v. New Hampshire Motor Transp. Assn., 552
U. S. 364, 371–373. Pp. 6−10.
2. This Court declines to decide in the case’s present, preenforcement posture whether Castle limits the way the Port can enforce the financial-capacity and truck-maintenance requirements upheld by the Ninth Circuit. Castle rebuffed a State’s attempt to bar a Cite as: 569 U. S. ____ (2013) 3
Syllabus
federally licensed motor carrier from its highways for past infringements of state safety regulations. But Castle does not prevent a
State from taking off the road a vehicle that is contemporaneously
out of compliance with such regulations. And at this juncture, there
is no basis for finding that the Port will actually use the concession
agreement’s penalty provision as Castle proscribes. Pp. 10−12.
660 F. 3d 384, reversed in part and remanded.
KAGAN, J., delivered the opinion for a unanimous Court. THOMAS, J.,
filed a concurring opinion. _________________
_________________
Cite as: 569 U. S. ____ (2013) 1
Opinion of the Court
NOTICE: This opinion is subject to formal revision before publication in the
preliminary print of the United States Reports. Readers are requested to
notify the Reporter of Decisions, Supreme Court of the United States, Washington, D. C. 20543, of any typographical or other formal errors, in order
that corrections may be made before the preliminary print goes to press.
SUPREME COURT OF THE UNITED STATES
No. 11–798
AMERICAN TRUCKING ASSOCIATIONS, INC.,
PETITIONER v. CITY OF LOS ANGELES,
CALIFORNIA, ET AL.
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE NINTH CIRCUIT
[June 13, 2013]
JUSTICE KAGAN delivered the opinion of the Court.
In this case, we consider whether federal law preempts
certain provisions of an agreement that trucking companies must sign before they can transport cargo at the Port
of Los Angeles. We hold that the Federal Aviation Administration Authorization Act of 1994 (FAAAA) expressly
preempts two of the contract’s provisions, which require
such a company to develop an off-street parking plan and
display designated placards on its vehicles. We decline to
decide in the case’s present, pre-enforcement posture
whether, under Castle v. Hayes Freight Lines, Inc., 348
U. S. 61 (1954), federal law governing licenses for interstate motor carriers prevents the Port from using the
agreement’s penalty clause to punish violations of other,
non-preempted provisions.
I
A
The Port of Los Angeles, a division of the City of Los
Angeles, is the largest port in the country. The Port owns
marine terminal facilities, which it leases to “terminal 2 AMERICAN TRUCKING ASSNS., INC. v. LOS ANGELES
Opinion of the Court
operators” (such as shipping lines and stevedoring companies) that load cargo onto and unload it from docking
ships. Short-haul trucks, called “drayage trucks,” move
the cargo into and out of the Port. The trucking companies providing those drayage services are all federally
licensed motor carriers. Before the events giving rise
to this case, they contracted with terminal operators to
transport cargo, but did not enter into agreements with
the Port itself.
The City’s Board of Harbor Commissioners runs the
Port pursuant to a municipal ordinance known as a tariff,
which sets out various regulations and charges. In the
late 1990’s, the Board decided to enlarge the Port’s facilities to accommodate more ships. Neighborhood and environmental groups objected to the proposed expansion,
arguing that it would increase congestion and air pollution
and decrease safety in the surrounding area. A lawsuit
they brought, and another they threatened, stymied the
Board’s development project for almost 10 years.
To address the community’s concerns, the Board implemented a Clean Truck Program beginning in 2007.
Among other actions, the Board devised a standard-form
“concession agreement” to govern the relationship between
the Port and any trucking company seeking to operate on
the premises. Under that contract, a company may
transport cargo at the Port in exchange for complying with
various requirements. The two directly at issue here
compel the company to (1) affix a placard on each truck
with a phone number for reporting environmental or
safety concerns (You’ve seen the type: “How am I driving?
213–867–5309”) and (2) submit a plan listing off-street
parking locations for each truck when not in service.
Three other provisions in the agreement, formerly disputed in this litigation, relate to the company’s financial
capacity, its maintenance of trucks, and its employment of
drivers. Cite as: 569 U. S. ____ (2013) 3
Opinion of the Court
The Board then amended the Port’s tariff to ensure that
every company providing drayage services at the facility
would enter into the concession agreement. The mechanism the Board employed is a criminal prohibition on
terminal operators. The amended tariff provides that “no
Terminal Operator shall permit access into any Terminal
in the Port of Los Angeles to any Drayage Truck unless
such Drayage Truck is registered under a Concession
[Agreement].” App. 105. A violation of that provision—
which occurs “each and every day” a terminal operator
provides access to an unregistered truck—is a misdemeanor. Id., at 86. It is punishable by a fine of up to $500
or a prison sentence of up to six months. Id., at 85–86.
The concession agreement itself spells out penalties for
any signatory trucking company that violates its requirements. When a company commits a “Minor Default,” the
Port may issue a warning letter or order the company to
undertake “corrective action,” complete a “course of . . .
training,” or pay the costs of the Port’s investigation. Id.,
at 81–82. When a company commits a “Major Default,”
the Port may also suspend or revoke the company’s right
to provide drayage services at the Port. Id., at 82. The
agreement, however, does not specify which breaches of
the contract qualify as “Major,” rather than “Minor.” And
the parties agree that the Port has never suspended or
revoked a trucking company’s license to operate at the
Port for a prior violation of one of the contract provisions
involved in this case. See Tr. of Oral Arg. 42–43, 49–51.
B
Petitioner American Trucking Associations, Inc. (ATA),
is a national trade association representing the trucking
industry, including drayage companies that operate at the
Port. ATA filed suit against the Port and City, seeking an
injunction against the five provisions of the concession
agreement discussed above. The complaint principally 4 AMERICAN TRUCKING ASSNS., INC. v. LOS ANGELES
Opinion of the Court
contended that §14501(c)(1) of the FAAAA expressly
preempts those requirements. That statutory section
states:
“[A] State [or local government] may not enact or enforce a law, regulation, or other provision having the
force and effect of law related to a price, route, or service of any motor carrier . . . with respect to the transportation of property.” 49 U. S. C. §14501(c)(1).1
ATA also offered a back-up argument: Even if the requirements are valid, ATA claimed, the Port may not
enforce them by withdrawing a defaulting company’s right
to operate at the Port. That argument rested on Castle v.
Hayes Freight Lines, Inc., 348 U. S. 61 (1954), which held
that Illinois could not bar a federally licensed motor car-
rier from its highways for prior violations of state safety
regulations. We reasoned in Castle that the State’s action
conflicted with federal law providing for certification of
motor carriers; and ATA argued here that a similar conflict would inhere in applying the concession agreement to
suspend or revoke a trucking company’s privileges. Following a bench trial, the District Court held that neither
§14501(c)(1) nor Castle prevents the Port from proceeding
with any part of its Clean Truck Program.
The Court of Appeals for the Ninth Circuit mainly affirmed. Most important for our purposes, the court held
that §14501(c)(1) does not preempt the agreement’s plac-
——————
1
ATA also contended that a separate provision, 49 U. S. C. §14506(a),
preempts the agreement’s placard requirement. That section bars state
and local governments from enacting or enforcing “any law, rule,
regulation[,] standard, or other provision having the force and effect of
law” that obligates a motor carrier to display any form of identification
other than those the Secretary of Transportation has required. Ibid.
The just-quoted language is the only part of §14506(a) disputed here,
and it is materially identical to language in §14501(c)(1). We focus on
§14501(c)(1) for ease of reference, but everything we say about that
provision also applies to §14506(a). Cite as: 569 U. S. ____ (2013) 5
Opinion of the Court
ard and parking requirements because they do not
“‘ha[ve] the force and effect of law.’” 660 F. 3d 384, 395
(2011) (quoting §14501(c)(1)). The court reasoned that
those requirements, rather than regulating the drayage
market, advance the Port’s own “business interest” in
“managing its facilities.” Id., at 401. Both provisions were
“designed to address [a] specific proprietary problem[]”—
the need to “increase the community good-will necessary
to facilitate Port expansion.” Id., at 406–407; see id., at
409. The Ninth Circuit also held the agreement’s
financial-capacity and truck-maintenance provisions not
preempted, for reasons not relevant here.2
 Section
14501(c)(1), the court decided, preempts only the contract’s
employment provision. Finally, the Ninth Circuit rejected
ATA’s claim that Castle bars the Port from applying the
agreement’s penalty clause to withdraw a trucking company’s right to operate at the facility. The court thought
Castle inapplicable because of the narrower exclusion in
this case: “Unlike a ban on using all of a State’s freeways,”
the court reasoned, “a limitation on access to a single Port
does not prohibit motor carriers” from generally participating in interstate commerce. 660 F. 3d, at 403.
We granted certiorari to resolve two questions: first,
whether §14501(c)(1) of the FAAAA preempts the concession agreement’s placard and parking provisions; and
second, whether Castle precludes reliance on the agreement’s penalty clause to suspend or revoke a trucking
company’s privileges. See 568 U. S. ___ (2013). Contrary
to the Ninth Circuit, we hold that the placard and parking
requirements are preempted as “provision[s] having the
force and effect of law.” That determination does not
——————
2
For those curious, the court held that the financial-capacity requirement is not “‘related to a [motor carrier’s] price, route, or service,’ ”
and that the truck-maintenance requirement falls within a statutory
exception for safety regulation. 660 F. 3d, at 395, 403–406 (quoting
§14501(c)(1)); see §14501(c)(2)(A) (safety exception). 6 AMERICAN TRUCKING ASSNS., INC. v. LOS ANGELES
Opinion of the Court
obviate the enforcement issue arising from Castle because
the Ninth Circuit’s rulings upholding the agreement’s
financial-capacity and truck-maintenance provisions have
now become final;3
 accordingly, the Port could try to apply
its penalty provision to trucking companies that have
violated those surviving requirements. But we nonetheless decline to address the Castle question because the
case’s pre-enforcement posture obscures the nature of the
agreement’s remedial scheme, rendering any decision at
this point a shot in the dark.
II
Section 14501(c)(1), once again, preempts a state “law,
regulation, or other provision having the force and effect of
law related to a price, route, or service of any motor carrier . . . with respect to the transportation of property.” All
parties agree that the Port’s placard and parking requirements relate to a motor carrier’s price, route, or service
with respect to transporting property. The only disputed
question is whether those requirements “hav[e] the force
and effect of law.” The Port claims that they do not, because the “concession contract is just [like] a private
agreement,” made to advance the Port’s commercial and
“proprietary interests.” Brief for Respondent City of Los
Angeles et al. 19 (Brief for City of Los Angeles) (internal
quotation marks omitted).4
——————
3
ATA’s petition for certiorari did not seek review of the Ninth Circuit’s determination that the truck-maintenance provision is valid. The
petition did ask us to consider the court’s ruling on the financialcapacity provision, but we declined to do so.
4
The Port’s brief occasionally frames the issue differently—as whether
a freestanding “market-participant exception” limits §14501(c)(1)’s
express terms. See Brief for City of Los Angeles 24. But at oral argument, the Port emphasized that the supposed exception it invoked in
fact derives from §14501(c)(1)’s “force and effect of law” language. See
Tr. of Oral Arg. 31 (“[W]hat we are calling the market participant
exception . . . is generally congruent with[ ] what is meant by Congress Cite as: 569 U. S. ____ (2013) 7
Opinion of the Court
We can agree with the Port on this premise: Section
14501(c)(1) draws a rough line between a government’s
exercise of regulatory authority and its own contract-based
participation in a market. We recognized that distinction
in American Airlines, Inc. v. Wolens, 513 U. S. 219 (1995),
when we construed another statute’s near-identical “force
and effect of law” language. That phrase, we stated, “connotes official, government-imposed policies” prescribing
“binding standards of conduct.” Id., at 229, n. 5 (internal
quotation marks omitted). And we contrasted that quintessential regulatory action to “contractual commitment[s]
voluntarily undertaken.” Id., at 229 (internal quotation
marks omitted). In Wolens, we addressed a State’s enforcement of an agreement between two private parties.
But the same reasoning holds if the government enters
into a contract just as a private party would—for example,
if a State (or City or Port) signs an agreement with a
trucking company to transport goods at a specified price.
See, e.g., Building & Constr. Trades Council v. Associated
Builders & Contractors of Mass./R. I., Inc., 507 U. S. 218,
233 (1993) (When a State acts as a purchaser of services,
“it does not ‘regulate’ the workings of the market . . . ;
it exemplifies them” (some internal quotation marks
omitted)). The “force and effect of law” language in
§14501(c)(1) excludes such everyday contractual arrangements from the clause’s scope. That phrasing targets the
State acting as a State, not as any market actor—or other-
wise said, the State acting in a regulatory rather than
proprietary mode.
But that statutory reading gets the Port nothing, because it exercised classic regulatory authority—complete
——————
by the term ‘force and effect of law’ ”); id., at 39–40 (“I’m . . . relying on
the language . . . force and effect of law,” which “invites a market
participant analysis”). We therefore have no occasion to consider
whether or when a preemption clause lacking such language would
except a state or local government’s proprietary actions. 8 AMERICAN TRUCKING ASSNS., INC. v. LOS ANGELES
Opinion of the Court
with the use of criminal penalties—in imposing the placard and parking requirements at issue here. Consider
again how those requirements work. They are, to be sure,
contained in contracts between the Port and trucking
companies. But those contracts do not stand alone, as the
result merely of the parties’ voluntary commitments. The
Board of Harbor Commissioners aimed to “require parties
who access Port land and terminals for purposes of pro-
viding drayage services” to enter into concession agreements with the Port. App. 108 (Board’s “Findings”). And
it accomplished that objective by amending the Port’s
tariff—a form of municipal ordinance—to provide that “no
Terminal Operator shall permit” a drayage truck to gain
“access into any Terminal in the Port” unless the truck is
“registered under” such a concession agreement. Id., at
105. A violation of that tariff provision is a violation of
criminal law. And it is punishable by a fine or a prison
sentence of up to six months. Id., at 85–86. So the contract here functions as part and parcel of a governmental
program wielding coercive power over private parties,
backed by the threat of criminal punishment.
That counts as action “having the force and effect of
law” if anything does. The Port here has not acted as a
private party, contracting in a way that the owner of an
ordinary commercial enterprise could mimic. Rather, it
has forced terminal operators—and through them, trucking companies—to alter their conduct by implementing a
criminal prohibition punishable by time in prison. In
some cases, the question whether governmental action has
the force of law may pose difficulties; the line between
regulatory and proprietary conduct has soft edges. But
this case takes us nowhere near those uncertain boundaries. Contractual commitments resulting not from ordinary bargaining (as in Wolens), but instead from the
threat of criminal sanctions manifest the government qua
government, performing its prototypical regulatory role. Cite as: 569 U. S. ____ (2013) 9
Opinion of the Court
The Port’s primary argument to the contrary, like the
Ninth Circuit’s, focuses on motive rather than means. The
Court of Appeals related how community opposition had
frustrated the Port’s expansion, and concluded that the
Clean Truck Program “respon[ded] to perceived business
necessity.” 660 F. 3d, at 407. The Port tells the identical
story, emphasizing that private companies have similar
business incentives to “adopt[] ‘green growth’ plans like
the Port’s.” Brief for City of Los Angeles 30. We have no
reason to doubt that account of events; we can assume the
Port acted to enhance goodwill and improve the odds of
achieving its business plan—just as a private company
might. But the Port’s intentions are not what matters.
That is because, as we just described, the Port chose a tool
to fulfill those goals which only a government can wield:
the hammer of the criminal law. See United Haulers
Assn., Inc. v. Oneida-Herkimer Solid Waste Mgmt. Auth.,
438 F. 3d 150, 157 (CA2 2006), aff ’d, 550 U. S. 330 (2007).
And when the government employs such a coercive mechanism, available to no private party, it acts with the force
and effect of law, whether or not it does so to turn a profit.
Only if it forgoes the (distinctively governmental) exercise
of legal authority may it escape §14501(c)(1)’s preemptive
scope.
The Port also tries another tack, reminding us that the
criminal sanctions here fall on terminal operators alone,
not on the trucking companies subject to the agreement’s
requirements; hence, the Port maintains, the matter of
“criminal penalties is a red herring.” Tr. of Oral Arg. 31;
see Brief for City of Los Angeles 39–40. But we fail to see
why the target of the sanctions makes any difference. The
Port selected an indirect but wholly effective means of
“requir[ing] parties . . . providing drayage services” to
display placards and submit parking plans: To wit, the
Port required terminal operators, on pain of criminal
penalties, to insist that the truckers make those commit-10 AMERICAN TRUCKING ASSNS., INC. v. LOS ANGELES
Opinion of the Court
ments. App. 108; see supra, at 3, 8. We have often rejected
efforts by States to avoid preemption by shifting their
regulatory focus from one company to another in the same
supply chain. See, e.g., Rowe v. New Hampshire Motor
Transp. Assn., 552 U. S. 364, 371–373 (2008) (finding
preemption under the FAAAA although the State’s requirements directly targeted retailers rather than motor
carriers); Engine Mfrs. Assn. v. South Coast Air Quality
Management Dist., 541 U. S. 246, 255 (2004) (finding
preemption under the Clean Air Act although the requirements directly targeted car buyers rather than
sellers). The same goes here. The Port made its regulation of drayage trucks mandatory by imposing criminal
penalties on the entities hiring all such trucks at the
facility. Slice it or dice it any which way, the Port thus
acted with the “force of law.”
III
Our rejection of the concession agreement’s placard and
parking requirements does not conclude this case. Two
other provisions of the agreement are now in effect: As
noted earlier, the Ninth Circuit upheld the financialcapacity and truck-maintenance requirements, and that
part of its decision has become final. See supra, at 5, and
n. 2. ATA argues that our holding in Castle limits the way
the Port can enforce those remaining requirements. According to ATA, the Port may not rely on the agreement’s
penalty provision to suspend or revoke the right of noncomplying trucking companies to operate on the premises.
As we have described, Castle rebuffed a State’s attempt
to bar a federally licensed motor carrier from its highways
for past infringements of state safety regulations. A federal statute, we explained, gave a federal agency the
authority to license interstate motor carriers, as well as a
carefully circumscribed power to suspend or terminate
those licenses for violations of law. That statute, we held, Cite as: 569 U. S. ____ (2013) 11
Opinion of the Court
implicitly prohibited a State from “tak[ing] action”—like a
ban on the use of its highways—“amounting to a suspension or revocation of an interstate carrier’s [federally]
granted right to operate.” 348 U. S., at 63–64.
The parties here dispute whether Castle restricts the
Port’s remedial authority. The Port echoes the Ninth
Circuit’s view that banning a truck from “all of a State’s
freeways” is meaningfully different from denying it “access
to a single Port.” 660 F. 3d, at 403; see Brief for City of
Los Angeles 49. ATA responds that because the Port is a
“crucial channel of interstate commerce,” Castle applies to
it just as much as to roads. Brief for Petitioner 18.
But we see another question here: Does the Port’s enforcement scheme involve curtailing drayage trucks’ operations in the way Castle prohibits, even assuming that
decision applies to facilities like this one? As just indicated, Castle puts limits on how a State or locality can punish
an interstate motor carrier for prior violations of trucking regulations (like the concession agreement’s requirements). Nothing we said there, however, prevents a State
from taking off the road a vehicle that is contemporaneously out of compliance with such regulations. Indeed,
ATA filed an amicus brief in Castle explaining that a
vehicle “that fails to comply with the state’s regulations
may be barred from the state’s highways.” Brief for ATA,
O. T 1954, No. 44, p. 12; see Brief for Respondent, id.,
p. 23 (A State may “stop and prevent from continuing on
the highway any motor vehicle which it finds not to be in
compliance”). And ATA reiterates that view here, as does
the United States as amicus curiae. See Reply Brief 22;
Brief for United States 29–30. So the Port would not
violate Castle if it barred a truck from operating at its
facilities to prevent an ongoing violation of the agreement’s requirements.
And at this juncture, we have no basis for finding that
the Port will ever use the agreement’s penalty provision 12 AMERICAN TRUCKING ASSNS., INC. v. LOS ANGELES
Opinion of the Court
for anything more than that. That provision, to be sure,
might be read to give the Port broader authority: As noted
earlier, the relevant text enables the Port to suspend
or revoke a trucking company’s right to provide drayage services at the facility as a “[r]emedy” for a “Major
Default.” App. 82; see supra, at 3. But the agreement
nowhere states what counts as a “Major Default”—and
specifically, whether a company’s breach of the financialcapacity or truck-maintenance requirements would qualify. And the Port has in fact never used its suspension or
revocation power to penalize a past violation of those
requirements. See Tr. of Oral Arg. 43, 50–51. Indeed, the
Port’s brief states that “it does not claim[] the authority to
punish past, cured violations of the requirements challenged here through suspension or revocation.” Brief for
City of Los Angeles 62 (internal quotation marks omitted).
So the kind of enforcement ATA fears, and believes inconsistent with Castle, might never come to pass at all.
In these circumstances, we decide not to decide ATA’s
Castle-based challenge. That claim, by its nature, attacks
the Port’s enforcement scheme. But given the preenforcement posture of this case, we cannot tell what that
scheme entails. It might look like the one forbidden in
Castle (as ATA anticipates), or else it might not (as the
Port assures us). We see no reason to take a guess now
about what the Port will do later. There will be time
enough to address the Castle question when, if ever, the
Port enforces its agreement in a way arguably violating
that decision.
IV
Section 14501(c)(1) of the FAAAA preempts the placard
and parking provisions of the Port’s concession agreement.
We decline to decide on the present record ATA’s separate
challenge, based on Castle, to that agreement’s penalty
provision. Accordingly, the judgment of the Ninth Circuit Cite as: 569 U. S. ____ (2013) 13
Opinion of the Court
is reversed in part, and the case is remanded for further
proceedings consistent with this opinion.
It is so ordered. _________________
_________________
Cite as: 569 U. S. ____ (2013) 1
THOMAS, J., concurring
SUPREME COURT OF THE UNITED STATES
No. 11–798
AMERICAN TRUCKING ASSOCIATIONS, INC.,
PETITIONER v. CITY OF LOS ANGELES,
CALIFORNIA, ET AL.
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE NINTH CIRCUIT
[June 13, 2013]
JUSTICE THOMAS, concurring.
I join the Court’s opinion in full. I write separately to
highlight a constitutional concern regarding §601 of the
Federal Aviation Administration Authorization Act of 1994
(FAAAA), 108 Stat. 1606, a statute the Court has now
considered twice this Term. See Dan’s City Used Cars,
Inc. v. Pelkey, 569 U. S. ___ (2013).
The Constitution grants Congress authority “[t]o regulate Commerce . . . among the several States.” Art. I, §8,
cl. 3 (emphasis added). Section 14501 of Title 49 is titled
“Federal authority over intrastate transportation.” (Emphasis added.) The tension between §14501 and the
Constitution is apparent, because the Constitution does
not give Congress power to regulate intrastate commerce.
United States v. Lopez, 514 U. S. 549, 587, n. 2 (1995)
(THOMAS, J., concurring). Nevertheless, §14501(c)(1)
purports to pre-empt any state or local law “related to
a price, route, or service of any motor carrier . . . with
respect to the transportation of property.” By its terms,
§14501(c) would pre-empt even a city ordinance establishing a uniform rate for most transportation services originating and ending inside city limits, so long as the services
were provided by a motor carrier. Such an extraordinary
assertion of congressional authority cannot be reconciled 2 AMERICAN TRUCKING ASSNS., INC. v. LOS ANGELES
THOMAS, J., concurring
with our constitutional system of enumerated powers.
The Supremacy Clause provides the constitutional basis
for the pre-emption of state laws. Art. VI, cl. 2 (“This
Constitution, and the Laws of the United States which
shall be made in Pursuance thereof . . . shall be the supreme Law of the Land”). Because the Constitution and
federal laws are supreme, conflicting state laws are without legal effect. See Crosby v. National Foreign Trade
Council, 530 U. S. 363, 372 (2000). However, the constitutional text leaves no doubt that only federal laws made “in
Pursuance” of the Constitution are supreme. See Gregory
v. Ashcroft, 501 U. S. 452, 460 (1991) (“As long as it is
acting within the powers granted it under the Constitution, Congress may impose its will on the States” (emphasis added)); Wyeth v. Levine, 555 U. S. 555, 583–587 (2009)
(THOMAS, J., concurring in judgment).
Given this limitation, Congress cannot pre-empt a state
law merely by promulgating a conflicting statute—the preempting statute must also be constitutional, both on its
face and as applied. As relevant here, if Congress lacks
authority to enact a law regulating a particular intrastate
activity, it follows that Congress also lacks authority to
pre-empt state laws regulating that activity. See U. S.
Const., Amdt. 10 (“The powers not delegated to the United
States by the Constitution, nor prohibited by it to the
States, are reserved to the States respectively, or to
the people”).
In this case, the Court concludes that “[s]ection
14501(c)(1) . . . preempts the placard and parking provisions of the Port’s concession agreement.” Ante, at 12.
Although respondents waived any argument that Congress lacks authority to regulate the placards and parking
arrangements of drayage trucks using the port, I doubt
that Congress has such authority. The Court has iden-
tified three categories of activity that Congress may
regulate under the Commerce Clause: (1) the use of the Cite as: 569 U. S. ____ (2013) 3
THOMAS, J., concurring
channels of interstate commerce; (2) the instrumentalities
of interstate commerce, and persons or things in interstate
commerce; and (3) “activities having a substantial relation
to interstate commerce . . . i.e., those activities that substantially affect interstate commerce.” Lopez, supra, at
558–559. Drayage trucks that carry cargo into and out of
the Port of Los Angeles undoubtedly operate within the
“channels of interstate commerce”—for that is what a port
is. Congress can therefore regulate conduct taking place
within the port. But it is doubtful whether Congress has
the power to decide where a drayage truck should park
once it has left the port or what kind of placard the truck
should display while offsite. Even under the “substantial
effects” test, which I have rejected as a “‘rootless and
malleable standard’ at odds with the constitutional design,” Gonzales v. Raich, 545 U. S. 1, 67 (dissenting opinion) (quoting United States v. Morrison, 529 U. S. 598,
627 (2000) (THOMAS, J., concurring)), it is difficult to say
that placards and parking arrangements substantially af-
fect interstate commerce. Congress made no findings
indicating that offsite parking—conduct that falls within
the scope of the States’ traditional police powers—
substantially affects interstate commerce. And I doubt
that it could. Nevertheless, because respondents did not
preserve a constitutional challenge to the FAAAA and
because I agree that the provisions in question have the
“force and effect of law,” I join the Court’s opinion.