UNITED STATES v. LOCKE, GOVERNOR OF WASHINGTON, et al.

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89 OCTOBER TERM, 1999
Syllabus
UNITED STATES v. LOCKE, GOVERNOR OF
WASHINGTON, et al.
certiorari to the united states court of appeals for
the ninth circuit
No. 98–1701. Argued December 7, 1999—Decided March 6, 2000*
After the supertanker Torrey Canyon spilled crude oil off the coast of
England in 1967, both Congress, in the Ports and Waterways Safety Act
of 1972 (PWSA), and the State of Washington enacted more stringent
regulations for tankers and provided for more comprehensive remedies
in the event of an oil spill. The ensuing question of federal pre-emption
of the State’s laws was addressed in Ray v. Atlantic Richfield Co., 435
U. S. 151. In 1989, the supertanker Exxon Valdez ran aground in
Alaska, causing the largest oil spill in United States history. Again,
both Congress and Washington responded. Congress enacted the Oil
Pollution Act of 1990 (OPA). The State created a new agency and di-
rected it to establish standards to provide the “best achievable protec-
tion” (BAP) from oil spill damages. That agency promulgated tanker
design, equipment, reporting, and operating requirements. Petitioner
International Association of Independent Tanker Owners (Intertanko),
a trade association of tanker operators, brought this suit seeking declar-
atory and injunctive relief against state and local officials responsible for
enforcing the BAP regulations. Upholding the regulations, the District
Court rejected Intertanko’s arguments that the BAP standards invaded
an area long pre-empted by the Federal Government. At the appeal
stage, the United States intervened on Intertanko’s behalf, contending
that the District Court’s ruling failed to give sufficient weight to the
substantial foreign affairs interests of the Federal Government. The
Ninth Circuit held that the State could enforce its laws, save one requir-
ing vessels to install certain navigation and towing equipment, which
was “virtually identical to” requirements declared pre-empted in Ray.
Held: Washington’s regulations regarding general navigation watch pro-
cedures, crew English language skills and training, and maritime cas-
ualty reporting are pre-empted by the comprehensive federal regula-
tory scheme governing oil tankers; these cases are remanded so the
*Together with No. 98–1706, International Association of Independent
Tanker Owners (Intertanko) v. Locke, Governor of Washington, et al.,
also on certiorari to the same court.

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90 UNITED STATES v. LOCKE
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validity of other Washington regulations may be assessed in light of the
considerable federal interest at stake. Pp. 99–117.
(a) The State has enacted legislation in an area where the federal
interest has been manifest since the beginning of the Republic and is
now well established. Congress has, beginning with the Tank Vessel
Act of 1936, enacted a series of statutes pertaining to maritime tanker
transports. These include the PWSA, Title I of which authorizes, but
does not require, the Coast Guard to enact measures for controlling
vessel traffic or for protecting navigation and the marine environment,
33 U. S. C. § 1223(a), and Title II of which, as amended, requires the
Coast Guard to issue regulations addressing the design, construction,
alteration, repair, maintenance, operation, equipping, personnel qualifi-
cation, and manning of covered vessels, 46 U. S. C. § 3703(a). Congress
later enacted OPA, Title I of which, among other things, imposes liabil-
ity for both removal costs and damages on parties responsible for an oil
spill, 33 U. S. C. § 2702, and includes two saving clauses preserving the
States’ authority to impose additional liability, requirements, and penal-
ties, §§ 2718(a) and (c). Congress has also ratified international agree-
ments in this area, including the International Convention of Standards
of Training Certification and Watchkeeping for Seafarers (STCW).
Pp. 99–103.
(b) In Ray, the Court held that the PWSA and Coast Guard regula-
tions promulgated under that Act pre-empted Washington’s pilotage re-
quirement, limitation on tanker size, and tanker design and construction
rules. The Ray Court’s interpretation of the PWSA is correct and con-
trolling here. Its basic analytic structure explains why federal pre-
emption analysis applies to the challenged regulations and allows scope
and due recognition for the traditional authority of the States and locali-
ties to regulate some matters of local concern. In narrowing the pre-
emptive effect given the PWSA in Ray, the Ninth Circuit placed more
weight on OPA’s saving clauses than they can bear. Like Title I of
OPA, in which they are found, the saving clauses are limited to regula-
tions governing liability and compensation for oil pollution, and do not
extend to rules regulating vessel operation, design, or manning. Thus,
the pre-emptive effect of the PWSA and its regulations is not affected
by OPA, and Ray’s holding survives OPA’s enactment undiminished.
The Ray Court’s prefatory observation that an “assumption” that the
States’ historic police powers were not to be superseded by federal law
unless that was the clear and manifest congressional purpose does not
mean that a presumption against pre-emption aids the Court’s analysis
here. An assumption of nonpre-emption is not triggered when the
State regulates in an area where there has been a history of significant
federal presence. The Ray Court held, among other things, that Con-

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91 Cite as: 529 U. S. 89 (2000)
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gress, in PWSA Title I, preserved state authority to regulate the peculi-
arities of local waters, such as depth and narrowness, if there is no
conflict with federal regulatory determinations, see 435 U. S., at 171–
172, 178, but further held that Congress, in PWSA Title II, mandated
uniform federal rules on the subjects or matters there specified, id., at
168. Thus, under Ray’s interpretation of the Title II provision now
found at 46 U. S. C. § 3703(a), only the Federal Government may regulate
the design, construction, alteration, repair, maintenance, operation,
equipping, personnel qualification, and manning of tankers. The Court
today reaffirms Ray’s holding on this point. Congress has left no room
for state regulation of these matters. See Fidelity Fed. Sav. & Loan
Assn. v. De la Cuesta, 458 U. S. 141. Although the Ray Court acknowl-
edged that the existence of some overlapping coverage between the two
PWSA titles may make it difficult to determine whether a pre-emption
question is controlled by conflict pre-emption principles, applicable gen-
erally to Title I, or by field pre-emption rules, applicable generally to
Title II, the Court declined to resolve every question by the greater
pre-emptive force of Title II. Thus, conflict pre-emption will be appli-
cable in some, although not all, cases. Useful inquiries in determining
which title governs include whether the regulation in question is justi-
fied by conditions unique to a particular port or waterway, see Ray, 435
U. S., at 175, or whether it is of limited extraterritorial effect, not requir-
ing the tanker to modify its primary conduct outside the specific body
of water purported to justify the local rule, see id., at 159–160, 171.
Pp. 103–112.
(c) The field pre-emption rule surrounding PWSA Title II and 46
U. S. C. § 3703(a) and the superseding effect of additional federal stat-
utes are illustrated by the pre-emption of four of Washington’s tanker
regulations, the attempted reach of which is well demonstrated by the
briefs and record. First, the imposition of a series of training require-
ments on a tanker’s crew does not address matters unique to Washing-
ton waters, but imposes requirements that control the staffing, opera-
tion, and manning of a tanker outside of those waters. The training
and drill requirements pertain to “operation” and “personnel qualifi-
cations” and so are pre-empted by § 3703(a). That training is a field
reserved to the Federal Government is further confirmed by the cir-
cumstance that the STCW Convention addresses crew “training” and
“qualification” requirements, and that the United States has enacted
crew training regulations. Second, the imposition of English language
proficiency requirements on a tanker’s crew is not limited to governing
local traffic or local peculiarities. It is pre-empted by § 3703(a) as a
“personnel qualification” and by 33 U. S. C. § 1228(a)(7), which requires
that any vessel operating in United States waters have at least one

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92 UNITED STATES v. LOCKE
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licensed deck officer on the navigation bridge who is capable of clearly
understanding English. Third, Washington’s general requirement that
the navigation watch consist of at least two licensed deck officers, a
helmsman, and a lookout is pre-empted as an attempt to regulate a tank-
er’s “operation” and “manning” under 46 U. S. C. § 3703(a). Fourth, the
requirement that vessels in Washington waters report certain marine
casualties regardless of where in the world they occurred cannot stand
in light of Coast Guard regulations on the same subject that Congress
intended be the sole source of a vessel’s reporting obligations, see
§§ 6101, 3717(a)(4). On remand, Washington may argue that certain of
its regulations, such as its watch requirement in times of restricted visi-
bility, are of limited extraterritorial effect, are necessary to address the
peculiarities of Puget Sound, and therefore are not subject to Title II
field pre-emption, but should instead be evaluated under Title I conflict
pre-emption analysis. Pp. 112–116.
(d) It is preferable that petitioners’ substantial arguments as to pre-
emption of the remaining Washington regulations be considered by the
Ninth Circuit or by the District Court within the framework this Court
has herein discussed. The United States did not participate in these
cases until appeal, and resolution of the litigation would benefit from
the development of a full record by all interested parties. If, pending
adjudication on remand, Washington threatens to begin enforcing its
regulations, the lower courts would weigh any stay application under
the appropriate legal standards in light of the principles discussed
herein and with recognition of the national interests at stake. Ulti-
mately, it is largely for Congress and the Coast Guard to confront
whether their regulatory scheme, which demands a high degree of
uniformity, is adequate. States, as well as environmental groups and
local port authorities, will participate in the process. See § 3703(a).
Pp. 116–117.
148 F. 3d 1053, reversed and remanded.
Kennedy, J., delivered the opinion for a unanimous Court.
David C. Frederick argued the cause for the United States
in No. 98–1701. With him on the briefs were Solicitor Gen-
eral Waxman, Acting Assistant Attorney General Ogden,
Deputy Solicitor General Kneedler, Douglas N. Letter, Mi-
chael Jay Singer, H. Thomas Byron III, David R. Andrews,
Judith Miller, Nancy E. McFadden, Paul M. Geier, Dale C.
Andrews, James S. Carmichael, Malcolm J. Williams, Jr.,
and Paul M. Wasserman. C. Jonathan Benner argued the

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93 Cite as: 529 U. S. 89 (2000)
Counsel
cause for petitioner in No. 98–1706. With him on the briefs
were Timi E. Nickerson and Sean T. Connaughton.
William Berggren Collins, Senior Assistant Attorney Gen-
eral of Washington, argued the cause for respondents in both
cases. With him on the brief for the state respondents were
Christine O. Gregoire, Attorney General, and Jay D. Geck,
Thomas C. Morrill, and Jerri Lynn Thomas, Assistant At-
torneys General. Jeffrey L. Needle filed a brief for respond-
ent Washington Environmental Council et al. With him on
the brief was John M. MacDonald.†
†Briefs of amici curiae urging reversal were filed for the Government
of Belgium et al. by Alex Blanton and Laurie C. Sahatjian; for the Ameri-
can Waterways Operators by Eldon V. C. Greenberg and Barbara L. Hol-
land; for the Baltic and International Maritime Council et al. by Dennis
L. Bryant, Charles L. Coleman III, Brian D. Starer, and Jovi Tenev; for
the International Chamber of Shipping et al. by William F. Sheehan, John
Townsend Rich, and Heather H. Anderson; for the Maritime Law Asso-
ciation of the United States by Howard M. McCormack, James Patrick
Cooney, and David J. Bederman; for the National Association of Water-
front Employers et al. by F. Edwin Froelich and Charles T. Carroll, Jr.;
for the Product Liability Advisory Council, Inc., et al. by Kenneth S. Gel-
ler, Charles Rothfeld, and Robin S. Conrad; and for the Washington Legal
Foundation by Daniel J. Popeo and R. Shawn Gunnarson.
Briefs of amici curiae urging affirmance were filed for the State of
California et al. by Bill Lockyer, Attorney General of California, Richard
M. Frank, Chief Assistant Attorney General, Mary E. Hackenbracht and
J. Matthew Rodriquez, Assistant Attorneys General, Dennis M. Eagan
and Michael W. Neville, Deputy Attorneys General, Maya B. Kara, Acting
Attorney General of the Northern Mariana Islands, and by the Attorneys
General for their respective States as follows: Bruce M. Botelho of Alaska,
Richard Blumenthal of Connecticut, Robert A. Butterworth of Florida,
Earl I. Anzai of Hawaii, James E. Ryan of Illinois, Richard P. Ieyoub of
Louisiana, Andrew Ketterer of Maine, Thomas F. Reilly of Massachusetts,
Mike Moore of Mississippi, Frankie Sue Del Papa of Nevada, John J.
Farmer, Jr., of New Jersey, Eliot Spitzer of New York, Michael F. Easley
of North Carolina, Betty D. Montgomery of Ohio, W. A. Drew Edmondson
of Oklahoma, Hardy Myers of Oregon, Sheldon Whitehouse of Rhode Is-
land, Charlie Condon of South Carolina, and Jan Graham of Utah; for
San Juan County, Washington, et al. by Randall K. Gaylord and Karen

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94 UNITED STATES v. LOCKE
Opinion of the Court
Justice Kennedy delivered the opinion of the Court.
The maritime oil transport industry presents ever-present,
all too real dangers of oil spills from tanker ships, spills
which could be catastrophes for the marine environment.
After the supertanker Torrey Canyon spilled its cargo of
120,000 tons of crude oil off the coast of Cornwall, England,
in 1967, both Congress and the State of Washington enacted
more stringent regulations for these tankers and provided
for more comprehensive remedies in the event of an oil spill.
The ensuing question of federal pre-emption of the State’s
laws was addressed by the Court in Ray v. Atlantic Rich-
field Co., 435 U. S. 151 (1978).
In 1989, the supertanker Exxon Valdez ran aground in
Prince William Sound, Alaska, and its cargo of more than 53
million gallons of crude oil caused the largest oil spill in
United States history. Again, both Congress and the State
of Washington responded. Congress enacted new statutory
provisions, and Washington adopted regulations governing
tanker operations and design. Today we must determine
whether these more recent state laws can stand despite the
comprehensive federal regulatory scheme governing oil
tankers. Relying on the same federal statute that con-
trolled the analysis in Ray, we hold that some of the State’s
regulations are pre-empted; as to the balance of the regula-
tions, we remand the case so their validity may be assessed
in light of the considerable federal interest at stake and in
conformity with the principles we now discuss.
E. Vedder; and for the Steamship Association of Southern California by
David E. R. Woolley and Thomas A. Russell.
Briefs of amici curiae were filed for the Government of Canada by Mar-
garet K. Pfeiffer; for the Pacific Coast Federation of Fishermen’s Associa-
tions et al. by Bryan P. Coluccio; for the Pacific Merchant Shipping Asso-
ciation by Sam D. Delich and James B. Nebel; for the Prince William
Sound Regional Citizens’ Advisory Council by Avrum M. Gross and Susan
A. Burke; and for the Puget Sound Steamship Operators Association et al.
by Richard W. Buchanan and Robert W. Nolting.

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Opinion of the Court
I
The State of Washington embraces some of the Nation’s
most significant waters and coastal regions. Its Pacific
Ocean seacoast consists, in large part, of wave-exposed rocky
headlands separated by stretches of beach. Washington
borders as well on the Columbia River estuary, dividing
Washington from Oregon. Two other large estuaries, Grays
Harbor and Willapa Bay, are also within Washington’s wa-
ters. Of special significance in these cases is the inland sea
of Puget Sound, a 2,500 square mile body of water consisting
of inlets, bays, and channels. More than 200 islands are lo-
cated within the sound, and it sustains fisheries and plant
and animal life of immense value to the Nation and to the
world.
Passage from the Pacific Ocean to the quieter Puget Sound
is through the Strait of Juan de Fuca, a channel 12 miles
wide and 65 miles long which divides Washington from the
Canadian Province of British Columbia. The international
boundary is located midchannel. Access to Vancouver, Can-
ada’s largest port, is through the strait. Traffic inbound
from the Pacific Ocean, whether destined to ports in the
United States or Canada, is routed through Washington’s
waters; outbound traffic, whether from a port in Washington
or Vancouver, is directed through Canadian waters. The
pattern had its formal adoption in a 1979 agreement entered
into by the United States and Canada. Agreement for a Co-
operative Vessel Traffic Management System for the Juan de
Fuca Region, 32 U. S. T. 377, T. I. A. S. No. 9706.
In addition to holding some of our vital waters, Washing-
ton is the site of major installations for the Nation’s oil indus-
try and the destination or shipping point for huge volumes
of oil and its end products. Refineries and product termi-
nals are located adjacent to Puget Sound in ports including
Cherry Point, Ferndale, Tacoma, and Anacortes. Canadian
refineries are found near Vancouver on Burrard Inlet and
the lower Fraser River. Crude oil is transported by sea to

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96 UNITED STATES v. LOCKE
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Puget Sound. Most is extracted from Alaska’s North Slope
reserve and is shipped to Washington on United States flag
vessels. Foreign-flag vessels arriving from nations such
as Venezuela and Indonesia also call at Washington’s oil
installations.
The bulk of oil transported on water is found in tankers,
vessels which consist of a group of tanks contained in a ship-
shaped hull, propelled by an isolated machinery plant at the
stern. The Court described the increase in size and num-
bers of these ships close to three decades ago in Askew v.
American Waterways Operators, Inc., 411 U. S. 325, 335
(1973), noting that the average vessel size increased from
16,000 tons during World War II to 76,000 tons in 1966.
(The term “tons” refers to “deadweight tons,” a way of mea-
suring the cargo-carrying capacity of the vessels.) Between
1955 and 1968, the world tanker fleet grew from 2,500 vessels
to 4,300. Ibid. By December 1973, 366 tankers in the
world tanker fleet were in excess of 175,000 tons, see 1
M. Tusiani, The Petroleum Shipping Industry 79 (1996), and
by 1998 the number of vessels considered “tankers” in the
merchant fleets of the world numbered 6,739, see U. S. Dept.
of Transp., Maritime Administration, Merchant Fleets of the
World 1 (Oct. 1998).
The size of these vessels, the frequency of tanker opera-
tions, and the vast amount of oil transported by vessels with
but one or two layers of metal between the cargo and the
water present serious risks. Washington’s waters have
been subjected to oil spills and further threatened by near
misses. In December 1984, for example, the tanker ARCO
Anchorage grounded in Port Angeles Harbor and spilled
239,000 gallons of Alaskan crude oil. The most notorious oil
spill in recent times was in Prince William Sound, Alaska,
where the grounding of the Exxon Valdez released more
than 11 million gallons of crude oil and, like the Torrey Can-
yon spill before it, caused public officials intense concern
over the threat of a spill.

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Opinion of the Court
Washington responded by enacting the state regulations
now in issue. The legislature created the Office of Marine
Safety, which it directed to establish standards for spill pre-
vention plans to provide “the best achievable protection
[BAP] from damages caused by the discharge of oil.” Wash.
Rev. Code § 88.46.040(3) (1994). The Office of Marine Safety
then promulgated the tanker design, equipment, reporting,
and operating requirements now subject to attack by pe-
titioners. Wash. Admin. Code (WAC) § 317–21–130 et seq.
(1999). A summary of the relevant regulations, as described
by the Court of Appeals, is set out in the Appendix, infra.
If a vessel fails to comply with the Washington rules,
possible sanctions include statutory penalties, restrictions of
the vessel’s operations in state waters, and a denial of entry
into state waters. Wash. Rev. Code §§ 88.46.070, 88.46.080,
88.46.090 (1994).
Petitioner International Association of Independent
Tanker Owners (Intertanko) is a trade association whose 305
members own or operate more than 2,000 tankers of both
United States and foreign registry. The organization repre-
sents approximately 80% of the world’s independently owned
tanker fleet; and an estimated 60% of the oil imported into
the United States is carried on Intertanko vessels. The
association brought this suit seeking declaratory and injunc-
tive relief against state and local officials responsible for
enforcing the BAP regulations. Groups interested in envi-
ronmental preservation intervened in defense of the laws.
Intertanko argued that Washington’s BAP standards in-
vaded areas long occupied by the Federal Government and
imposed unique requirements in an area where national uni-
formity was mandated. Intertanko further contended that
if local political subdivisions of every maritime nation were
to impose differing regulatory regimes on tanker operations,
the goal of national governments to develop effective in-
ternational environmental and safety standards would be
defeated.

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Although the United States declined to intervene when
the case was in the District Court, the governments of 13
ocean-going nations expressed concerns through a diplomatic
note directed to the United States. Intertanko lodged a
copy of the note with the District Court. The concerned
governments represented that “legislation by the State of
Washington on tanker personnel, equipment and operations
would cause inconsistency between the regulatory regime of
the US Government and that of an individual State of the
US. Differing regimes in different parts of the US would
create uncertainty and confusion. This would also set an
unwelcome precedent for other Federally administered coun-
tries.” Note Verbale from the Royal Danish Embassy to
the U. S. Dept. of State 1 (June 14, 1996).
The District Court rejected all of Intertanko’s arguments
and upheld the state regulations. International Assn. of
Independent Tanker Owners (Intertanko) v. Lowry, 947
F. Supp. 1484 (WD Wash. 1996). The appeal followed, and
at that stage the United States intervened on Intertanko’s
behalf, contending that the District Court’s ruling failed to
give sufficient weight to the substantial foreign affairs inter-
ests of the Federal Government. The United States Court
of Appeals for the Ninth Circuit held that the State could
enforce its laws, save the one requiring the vessels to install
certain navigation and towing equipment. 148 F. 3d 1053
(1998). The Court of Appeals reasoned that this require-
ment, found in WAC § 317–21–265, was “virtually identical
to” requirements declared pre-empted in Ray v. Atlantic
Richfield Co., 435 U. S. 151 (1978). 148 F. 3d, at 1066. Over
Judge Graber’s dissent, the Court of Appeals denied peti-
tions for rehearing en banc. 159 F. 3d 1220 (1998). Judge
Graber, although unwilling, without further analysis, to con-
clude that the panel reached the wrong result, argued that
the opinion was “incorrect in two exceptionally important
respects: (1) The opinion places too much weight on two
clauses in Title I of OPA 90 [The Oil Pollution Act of 1990]

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that limit OPA 90’s preemptive effect. (2) Portions of the
opinion that discuss the Coast Guard regulations are incon-
sistent with Ninth Circuit and Supreme Court precedent.”
Id., at 1221. We granted certiorari and now reverse. 527
U. S. 1063 (1999).
II
The State of Washington has enacted legislation in an area
where the federal interest has been manifest since the begin-
ning of our Republic and is now well established. The au-
thority of Congress to regulate interstate navigation, with-
out embarrassment from intervention of the separate States
and resulting difficulties with foreign nations, was cited in
the Federalist Papers as one of the reasons for adopting the
Constitution. E. g., The Federalist Nos. 44, 12, 64. In 1789,
the First Congress enacted a law by which vessels with a
federal certificate were entitled to “the benefits granted by
any law of the United States.” Act of Sept. 1, 1789, ch. 11,
§ 1, 1 Stat. 55. The importance of maritime trade and the
emergence of maritime transport by steamship resulted in
further federal licensing requirements enacted to promote
trade and to enhance the safety of crew members and passen-
gers. See Act of July 7, 1838, ch. 191, 5 Stat. 304; Act of
Mar. 3, 1843, ch. 94, 5 Stat. 626. In 1871, Congress enacted
a comprehensive scheme of regulation for steam powered
vessels, including provisions for licensing captains, chief
mates, engineers, and pilots. Act of Feb. 28, 1871, ch. 100,
16 Stat. 440.
The Court in Cooley v. Board of Wardens of Port of Phila-
delphia ex rel. Soc. for Relief of Distressed Pilots, 12 How.
299 (1852), stated that there would be instances in which
state regulation of maritime commerce is inappropriate even
absent the exercise of federal authority, although in the case
before it the Court found the challenged state regulations
were permitted in light of local needs and conditions.
Where Congress had acted, however, the Court had little
difficulty in finding state vessel requirements were pre-

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100 UNITED STATES v. LOCKE
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empted by federal laws which governed the certification of
vessels and standards of operation. Gibbons v. Ogden, 9
Wheat. 1 (1824), invalidated a New York law that attempted
to grant a monopoly to operate steamboats on the ground it
was inconsistent with the coasting license held by the vessel
owner challenging the exclusive franchise. And in Sinnot v.
Davenport, 22 How. 227 (1859), the Court decided that the
federal license held by the vessel contained “the only guards
and restraints, which Congress has seen fit to annex to the
privileges of ships and vessels engaged in the coasting
trade.” Id., at 241. The Court went on to explain that in
such a circumstance, state laws on the subject must yield:
“In every such case, the act of Congress or treaty is supreme;
and the law of the State, though enacted in the exercise of
powers not controverted, must yield to it.” Id., at 243.
Against this background, Congress has enacted a series of
statutes pertaining to maritime tanker transports and has
ratified international agreements on the subject. We begin
by referring to the principal statutes and international in-
struments discussed by the parties.
1. The Tank Vessel Act.
The Tank Vessel Act of 1936, 49 Stat. 1889, enacted specific
requirements for operation of covered vessels. The Act pro-
vided that “[i]n order to secure effective provisions against
the hazards of life and property,” additional federal rules
could be adopted with respect to the “design and construc-
tion, alteration, or repair of such vessels,” “the operation of
such vessels,” and “the requirements of the manning of such
vessels and the duties and qualifications of the officers and
crews thereof.” The purpose of the Act was to establish “a
reasonable and uniform set of rules and regulations concern-
ing . . . vessels carrying the type of cargo deemed danger-
ous.” H. R. Rep. No. 2962, 74th Cong., 2d Sess., 2 (1936).
The Tank Vessel Act was the primary source for regulating

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tank vessels for the next 30 years, until the Torrey Canyon
grounding led Congress to take new action.
2. The Ports and Waterways Safety Act of 1972.
Responding to the Torrey Canyon spill, Congress enacted
the Ports and Waterways Safety Act of 1972 (PWSA). The
Act, as amended by the Port and Tanker Safety Act of 1978,
92 Stat. 1471, contains two somewhat overlapping titles, both
of which may, as the Ray Court explained, preclude enforce-
ment of state laws, though not by the same pre-emption anal-
ysis. Title I concerns vessel traffic “in any port or place
under the jurisdiction of the United States.” 110 Stat. 3934,
33 U. S. C. § 1223(a)(1) (1994 ed., Supp. III). Under Title I,
the Coast Guard may enact measures for controlling vessel
traffic or for protecting navigation and the marine environ-
ment, but it is not required to do so. Ibid.
Title II does require the Coast Guard to issue regulations,
regulations addressing the “design, construction, alteration,
repair, maintenance, operation, equipping, personnel qualifi-
cation, and manning of vessels . . . that may be necessary for
increased protection against hazards to life and property, for
navigation and vessel safety, and for enhanced protection of
the marine environment.” 46 U. S. C. § 3703(a).
The critical provisions of the PWSA described above re-
main operative, but the Act has been amended, most signifi-
cantly by the Oil Pollution Act of 1990 (OPA), 104 Stat. 484.
OPA, enacted in response to the Exxon Valdez spill, requires
separate discussion.
3. The Oil Pollution Act of 1990.
The OPA contains nine titles, two having the most signifi-
cance for these cases. Title I is captioned “Oil Pollution Lia-
bility, and Compensation” and adds extensive new provisions
to the United States Code. See 104 Stat. 2375, 33 U. S. C.
§ 2701 et seq. (1994 ed. and Supp. III). Title I imposes lia-
bility (for both removal costs and damages) on parties re-

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102 UNITED STATES v. LOCKE
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sponsible for an oil spill. § 2702. Other provisions provide
defenses to, and limitations on, this liability. 33 U. S. C.
§§ 2703, 2704. Of considerable importance to these cases are
OPA’s saving clauses, found in Title I of the Act, § 2718, and
to be discussed below.
Title IV of OPA is entitled “Prevention and Removal.”
For the most part, it amends existing statutory provisions
or instructs the Secretary of Transportation (whose depart-
ments include the Coast Guard) to take action under previ-
ous grants of rulemaking authority. For example, Title IV
instructs the Coast Guard to require reporting of marine cas-
ualties resulting in a “significant harm to the environment.”
46 U. S. C. § 6101(a)(5) (1994 ed. and Supp. V). Title IV fur-
ther requires the Secretary to issue regulations to define
those areas, including Puget Sound, on which single hulled
tankers shall be escorted by other vessels. 104 Stat. 523.
By incremental dates specified in the Act, all covered tanker
vessels must have a double hull. 46 U. S. C. § 3703a.
4. Treaties and International Agreements.
The scheme of regulation includes a significant and intri-
cate complex of international treaties and maritime agree-
ments bearing upon the licensing and operation of vessels.
We are advised by the United States that the international
regime depends upon the principle of reciprocity. That is to
say, the certification of a vessel by the government of its
own flag nation warrants that the ship has complied with
international standards, and vessels with those certificates
may enter ports of the signatory nations. Brief for United
States 3.
Illustrative of treaties and agreements to which the
United States is a party are the International Convention
for the Safety of Life at Sea, 1974, 32 U. S. T. 47, T. I. A. S.
No. 9700, the International Convention for Prevention of Pol-
lution from Ships, 1973, S. Exec. Doc. C, 93–1, 12 I. L. M.
1319, as amended by 1978 Protocol, S. Exec. Doc. C, 96–1, 17

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I. L. M. 546, and the International Convention of Standards
of Training, Certification and Watchkeeping for Seafarers,
With Annex, 1978 (STCW), S. Exec. Doc. EE, 96–1, C. T. I. A.
No. 7624.
The United States argues that these treaties, as the su-
preme law of the land, have pre-emptive force over the state
regulations in question here. We need not reach that issue
at this stage of the case because the state regulations we
address in detail below are pre-empted by federal statute
and regulations. The existence of the treaties and agree-
ments on standards of shipping is of relevance, of course, for
these agreements give force to the longstanding rule that
the enactment of a uniform federal scheme displaces state
law, and the treaties indicate Congress will have demanded
national uniformity regarding maritime commerce. See
Ray, 435 U. S., at 166 (recognizing Congress anticipated “ar-
riving at international standards for building tank vessels”
and understanding “the Nation was to speak with one voice”
on these matters). In later proceedings, if it is deemed nec-
essary for full disposition of the case, it should be open to
the parties to argue whether the specific international agree-
ments and treaties are of binding, pre-emptive force. We do
not reach those questions, for it may be that pre-emption
principles applicable to the basic federal statutory structure
will suffice, upon remand, for a complete determination.
III
In Ray v. Atlantic Richfield, supra, the Court was asked
to review, in light of an established federal and international
regulatory scheme, comprehensive tanker regulations im-
posed by the State of Washington. The Court held that the
PWSA and Coast Guard regulations promulgated under that
Act pre-empted a state pilotage requirement, Washington’s
limitation on tanker size, and tanker design and construc-
tion rules.

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In these cases, petitioners relied on Ray to argue that
Washington’s more recent state regulations were pre-
empted as well. The Court of Appeals, however, concluded
that Ray retained little validity in light of subsequent action
by Congress. We disagree. The Ray Court’s interpreta-
tion of the PWSA is correct and controlling. Its basic ana-
lytic structure explains why federal pre-emption analysis ap-
plies to the challenged regulations and allows scope and due
recognition for the traditional authority of the States and
localities to regulate some matters of local concern.
At the outset, it is necessary to explain that the essential
framework of Ray, and of the PWSA which it interpreted,
are of continuing force, neither having been superseded by
subsequent authority relevant to these cases. In narrowing
the pre-emptive effect given the PWSA in Ray, the Court of
Appeals relied upon OPA’s saving clauses, finding in their
language a return of authority to the States. Title I of OPA
contains two saving clauses, stating:
“(a) Preservation of State authorities . . .
“Nothing in this Act or the Act of March 3, 1851
shall—
“(1) affect, or be construed or interpreted as pre-
empting, the authority of any State or political sub-
division thereof from imposing any additional liability
or requirements with respect to—
“(A) the discharge of oil or other pollution by oil
within such State . . . .
. . . . .
“(c) Additional requirements and liabilities; penalties
“Nothing in this Act, the Act of March 3, 1851 (46
U. S. C. 183 et seq.), or section 9509 of [the Internal Rev-
enue Code of 1986 (26 U. S. C. 9509)], shall in any way
affect, or be construed to affect, the authority of the
United States or any State or political subdivision
thereof—

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“(1) to impose additional liability or additional
requirements
. . . . .
“relating to the discharge, or substantial threat of a
discharge, of oil.” 33 U. S. C. § 2718.
The Court of Appeals placed more weight on the saving
clauses than those provisions can bear, either from a textual
standpoint or from a consideration of the whole federal regu-
latory scheme of which OPA is but a part.
The saving clauses are found in Title I of OPA, captioned
Oil Pollution Liability and Compensation and creating a lia-
bility scheme for oil pollution. In contrast to the Washing-
ton rules at issue here, Title I does not regulate vessel opera-
tion, design, or manning. Placement of the saving clauses
in Title I of OPA suggests that Congress intended to pre-
serve state laws of a scope similar to the matters contained
in Title I of OPA, not all state laws similar to the matters
covered by the whole of OPA or to the whole subject of mari-
time oil transport. The evident purpose of the saving
clauses is to preserve state laws which, rather than imposing
substantive regulation of a vessel’s primary conduct, estab-
lish liability rules and financial requirements relating to oil
spills. See Gutierrez v. Ada, 528 U. S. 250, 255 (2000) (words
of a statute should be interpreted consistent with their
neighbors to avoid giving unintended breadth to an Act of
Congress).
Our conclusion is fortified by Congress’ decision to limit
the saving clauses by the same key words it used in declaring
the scope of Title I of OPA. Title I of OPA permits recovery
of damages involving vessels “from which oil is discharged,
or which pos[e] the substantial threat of a discharge of oil.”
33 U. S. C. § 2702(a). The saving clauses, in parallel manner,
permit States to impose liability or requirements “relating
to the discharge, or substantial threat of a discharge, of oil.”
§ 2718(c). In its titles following Title I, OPA addresses mat-
ters including licensing and certificates of registry, 104 Stat.

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106 UNITED STATES v. LOCKE
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509; duties of senior licensed officers to relieve the master,
id., at 511; manning standards for foreign vessels, id., at 513;
reporting of marine casualties, ibid.; minimum standards for
plating thickness, id., at 515; tank vessel manning require-
ments, id., at 517; and tank vessel construction standards,
id., at 517–518, among other extensive regulations. If Con-
gress had intended to disrupt national uniformity in all of
these matters, it would not have done so by placement of the
saving clauses in Title I.
The saving clauses are further limited in effect to “this
Act, the Act of March 3, 1851 . . . , or section 9509 of [the
Internal Revenue Code].” §§ 2718(a) and (c). These ex-
plicit qualifiers are inconsistent with interpreting the saving
clauses to alter the pre-emptive effect of the PWSA or regu-
lations promulgated thereunder. The text of the statute in-
dicates no intent to allow States to impose wide-ranging reg-
ulation of the at-sea operation of tankers. The clauses may
preserve a State’s ability to enact laws of a scope similar to
Title I, but do not extend to subjects addressed in the other
titles of the Act or other acts.
Limiting the saving clauses as we have determined re-
spects the established federal-state balance in matters of
maritime commerce between the subjects as to which the
States retain concurrent powers and those over which the
federal authority displaces state control. We have upheld
state laws imposing liability for pollution caused by oil spills.
See Askew v. American Waterways Operators, Inc., 411
U. S., at 325. Our view of OPA’s saving clauses preserves
this important role for the States, which is unchallenged
here. We think it quite unlikely that Congress would use a
means so indirect as the saving clauses in Title I of OPA to
upset the settled division of authority by allowing States to
impose additional unique substantive regulation on the at-
sea conduct of vessels. We decline to give broad effect to
saving clauses where doing so would upset the careful regu-
latory scheme established by federal law. See, e. g., Morales

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v. Trans World Airlines, Inc., 504 U. S. 374, 385 (1992);
American Telephone & Telegraph Co. v. Central Office Tele-
phone, Inc., 524 U. S. 214, 227–228 (1998).
From the text of OPA and the long-established under-
standing of the appropriate balance between federal and
state regulation of maritime commerce, we hold that the
pre-emptive effect of the PWSA and regulations promul-
gated under it are not affected by OPA. We doubt Congress
will be surprised by our conclusion, for the Conference
Report on OPA shared our view that the statute “does not
disturb the Supreme Court’s decision in Ray v. Atlantic
Richfield Co., 435 U. S. 151 (1978).” H. R. Conf. Rep.
No. 101–653, p. 122 (1990). The holding in Ray also survives
the enactment of OPA undiminished, and we turn to a de-
tailed discussion of that case.
As we mentioned above, the Ray Court confronted a claim
by the operator of a Puget Sound refinery that federal law
precluded Washington from enforcing laws imposing certain
substantive requirements on tankers. The Ray Court pref-
aced its analysis of the state regulations with the following
observation:
“The Court’s prior cases indicate that when a State’s
exercise of its police power is challenged under the Su-
premacy Clause, ‘we start with the assumption that the
historic police powers of the States were not to be su-
perseded by the Federal Act unless that was the clear
and manifest purpose of Congress.’ Rice v. Santa Fe
Elevator Corp., 331 U. S. 218, 230 (1947).” 435 U. S.,
at 157.
The fragmentary quote from Rice v. Santa Fe Elevator
Corp., 331 U. S. 218 (1947), does not support the scope given
to it by the Court of Appeals or by respondents.
Ray quoted but a fragment of a much longer paragraph
found in Rice. The quoted fragment is followed by exten-
sive and careful qualifications to show the different ap-

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108 UNITED STATES v. LOCKE
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proaches taken by the Court in various contexts. We need
not discuss that careful explanation in detail, however. To
explain the full intent of the Rice quotation, it suffices to
quote in full the sentence in question and two sentences pre-
ceding it. The Rice opinion stated: “The question in each
case is what the purpose of Congress was. Congress legis-
lated here in a field which the States have traditionally occu-
pied. So we start with the assumption that the historic po-
lice powers of the States were not to be superseded by the
Federal Act unless that was the clear and manifest purpose
of Congress.” 331 U. S., at 230 (citations omitted).
The qualification given by the word “so” and by the pre-
ceding sentences in Rice are of considerable consequence.
As Rice indicates, an “assumption” of nonpre-emption is not
triggered when the State regulates in an area where there
has been a history of significant federal presence. See also
Jones v. Rath Packing Co., 430 U. S. 519, 525 (1977) (“as-
sumption” is triggered where “the field which Congress is
said to have pre-empted has been traditionally occupied by
the States”); Medtronic, Inc. v. Lohr, 518 U. S. 470, 485 (1996)
(citing Rice in case involving medical negligence, a subject
historically regulated by the States). In Ray, and in the
case before us, Congress has legislated in the field from the
earliest days of the Republic, creating an extensive federal
statutory and regulatory scheme.
The state laws now in question bear upon national and
international maritime commerce, and in this area there is
no beginning assumption that concurrent regulation by the
State is a valid exercise of its police powers. Rather, we
must ask whether the local laws in question are consistent
with the federal statutory structure, which has as one of its
objectives a uniformity of regulation for maritime commerce.
No artificial presumption aids us in determining the scope of
appropriate local regulation under the PWSA, which, as we
discuss below, does preserve, in Title I of that Act, the his-
toric role of the States to regulate local ports and waters

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under appropriate circumstances. At the same time, as we
also discuss below, uniform, national rules regarding general
tanker design, operation, and seaworthiness have been man-
dated by Title II of the PWSA.
The Ray Court confirmed the important proposition that
the subject and scope of Title I of the PWSA allows a State
to regulate its ports and waterways, so long as the regula-
tion is based on “the peculiarities of local waters that call for
special precautionary measures.” 435 U. S., at 171. Title I
allows state rules directed to local circumstances and prob-
lems, such as water depth and narrowness, idiosyncratic to
a particular port or waterway. Ibid. There is no pre-
emption by operation of Title I itself if the state regulation
is so directed and if the Coast Guard has not adopted regula-
tions on the subject or determined that regulation is unnec-
essary or inappropriate. This principle is consistent with
recognition of an important role for States and localities in
the regulation of the Nation’s waterways and ports. E. g.,
Cooley, 12 How., at 319 (recognizing state authority to adopt
plans “applicable to the local peculiarities of the ports within
their limits”). It is fundamental in our federal structure
that States have vast residual powers. Those powers, un-
less constrained or displaced by the existence of federal au-
thority or by proper federal enactments, are often exercised
in concurrence with those of the National Government. Mc-
Culloch v. Maryland, 4 Wheat. 316 (1819).
As Ray itself made apparent, the States may enforce rules
governed by Title I of the PWSA unless they run counter to
an exercise of federal authority. The analysis under Title I
of the PWSA, then, is one of conflict pre-emption, which
occurs “when compliance with both state and federal law
is impossible, or when the state law ‘stands as an obstacle
to the accomplishment and execution of the full purposes
and objective of Congress.’ ” California v. ARC America
Corp., 490 U. S. 93, 100–101 (1989) (citations omitted). In
this context, Coast Guard regulations are to be given pre-

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110 UNITED STATES v. LOCKE
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emptive effect over conflicting state laws. City of New York
v. FCC, 486 U. S. 57, 63–64 (1988) (“ ‘[A] federal agency acting
within the scope of its congressionally delegated authority
may pre-empt state regulation’ and hence render unenforce-
able state or local laws that are otherwise not inconsistent
with federal law”). Ray defined the relevant inquiry for
Title I pre-emption as whether the Coast Guard has promul-
gated its own requirement on the subject or has decided that
no such requirement should be imposed at all. 435 U. S., at
171–172; see also id., at 178 (“ ‘[W]here failure of . . . federal
officials affirmatively to exercise their full authority takes on
the character of a ruling that no such regulation is appro-
priate or approved pursuant to the policy of the statute,’
States are not permitted to use their police power to enact
such a regulation. Bethlehem Steel Co. v. New York State
Labor Relations Board, 330 U. S. 767, 774 (1947)”). Ray
also recognized that, even in the context of a regulation re-
lated to local waters, a federal official with an overview of
all possible ramifications of a particular requirement might
be in the best position to balance all the competing interests.
Id., at 177.
While Ray explained that Congress, in Title I of the
PWSA, preserved state authority to regulate the peculiari-
ties of local waters if there was no conflict with federal regu-
latory determinations, the Court further held that Congress,
in Title II of the PWSA, mandated federal rules on the sub-
jects or matters there specified, demanding uniformity. Id.,
at 168 (“Title II leaves no room for the States to impose
different or stricter design requirements than those which
Congress has enacted with the hope of having them interna-
tionally adopted or has accepted as the result of international
accord. A state law in this area . . . would frustrate the
congressional desire of achieving uniform, international
standards”). Title II requires the Coast Guard to impose
national regulations governing the general seaworthiness of
tankers and their crews. Id., at 160. Under Ray’s inter-

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pretation of the Title II PWSA provision now found at 46
U. S. C. § 3703(a), only the Federal Government may regulate
the “design, construction, alteration, repair, maintenance, op-
eration, equipping, personnel qualification, and manning” of
tanker vessels.
In Ray, this principle was applied to hold that Washing-
ton’s tanker design and construction rules were pre-empted.
Those requirements failed because they were within a field
reserved for federal regulation under 46 U. S. C. § 391a (1982
ed.), the predecessor to § 3703(a). We reaffirm Ray’s holding
on this point. Contrary to the suggestion of the Court of
Appeals, the field of pre-emption established by § 3703(a)
cannot be limited to tanker “design” and “construction,”
terms which cannot be read in isolation from the other sub-
jects found in that section. Title II of the PWSA covers
“design, construction, alteration, repair, maintenance, opera-
tion, equipping, personnel qualification, and manning” of
tanker vessels. Ibid. Congress has left no room for state
regulation of these matters. See Fidelity Fed. Sav. & Loan
Assn. v. De la Cuesta, 458 U. S. 141 (1982) (explaining field
pre-emption). As the Ray Court stated: “[T]he Supremacy
Clause dictates that the federal judgment that a vessel is
safe to navigate United States waters prevail over the con-
trary state judgment. Enforcement of the state require-
ments would at least frustrate what seems to us to be the
evident congressional intention to establish a uniform federal
regime controlling the design of oil tankers.” 435 U. S., at
165.
The existence of some overlapping coverage between the
two titles of the PWSA may make it difficult to determine
whether a pre-emption question is controlled by conflict pre-
emption principles, applicable generally to Title I, or by field
pre-emption rules, applicable generally to Title II. The Ray
Court acknowledged the difficulty, but declined to resolve
every question by the greater pre-emptive force of Title II.
We follow the same approach, and conflict pre-emption under

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Title I will be applicable in some, although not all, cases.
We recognize that the terms used in § 3703(a) are quite
broad. In defining their scope, and the scope of the result-
ing field pre-emption, it will be useful to consider the type
of regulations the Secretary has actually promulgated under
the section, as well as the section’s list of specific types of
regulation that must be included. Useful inquiries include
whether the rule is justified by conditions unique to a partic-
ular port or waterway. See id., at 175 (a Title I regulation
is one “based on water depth in Puget Sound or on other
local peculiarities”). Furthermore, a regulation within the
State’s residual powers will often be of limited extraterrito-
rial effect, not requiring the tanker to modify its primary
conduct outside the specific body of water purported to jus-
tify the local rule. Limited extraterritorial effect explains
why Ray upheld a state rule requiring a tug escort for cer-
tain vessels, id., at 171, and why state rules requiring a reg-
istered vessel (i. e., one involved in foreign trade) to take on
a local pilot have historically been allowed, id., at 159–160.
Local rules not pre-empted under Title II of the PWSA pose
a minimal risk of innocent noncompliance, do not affect ves-
sel operations outside the jurisdiction, do not require adjust-
ment of systemic aspects of the vessel, and do not impose a
substantial burden on the vessel’s operation within the local
jurisdiction itself.
IV
The field pre-emption rule surrounding Title II and
§ 3703(a) and the superseding effect of additional federal
statutes are illustrated by the pre-emption of four of Wash-
ington’s tanker regulations. We address these because the
attempted reach of the state rules is well demonstrated by
the briefs and record before us; other parts of the state regu-
latory scheme can be addressed on remand.
First, Washington imposes a series of training require-
ments on a tanker’s crew. WAC § 317–21–230; see also Ap-
pendix, infra, at 118. A covered vessel is required to certify

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that its crew has “complete[d] a comprehensive training pro-
gram approved by the [State].” The State requires the ves-
sel’s master to “be trained in shipboard management” and
licensed deck officers to be trained in bridge resource man-
agement, automated radar plotting aids, shiphandling, crude
oil washing, inert gas systems, cargo handling, oil spill pre-
vention and response, and shipboard fire fighting. The state
law mandates a series of “weekly,” “monthly,” and “quar-
terly” drills.
This state requirement under WAC § 317–21–230 does not
address matters unique to the waters of Puget Sound. On
the contrary, it imposes requirements that control the
staffing, operation, and manning of a tanker outside of Wash-
ington’s waters. The training and drill requirements per-
tain to “operation” and “personnel qualifications” and so are
pre-empted by 46 U. S. C. § 3703(a). Our conclusion that
training is a field reserved to the Federal Government re-
ceives further confirmation from the circumstance that the
STCW Convention addresses “training” and “qualification”
requirements of the crew, Art. VI, and that the United
States has enacted crew training requirements. E. g., 46
CFR pts. 10, 12, 13, 15 (1999).
The second Washington rule we find pre-empted is WAC
§ 317–21–250; see also Appendix, infra, at 119. Washington
imposes English language proficiency requirements on a
tanker’s crew. This requirement will dictate how a tanker
operator staffs the vessel even from the outset of the voyage,
when the vessel may be thousands of miles from Puget
Sound. It is not limited to governing local traffic or local
peculiarities. The State’s attempted rule is a “personnel
qualification” pre-empted by § 3703(a) of Title II. In
addition, there is another federal statute, 33 U. S. C.
§ 1228(a)(7), on the subject. It provides: “[N]o vessel . . .
shall operate in the navigable waters of the United
States . . . , if such vessel . . . while underway, does not have
at least one licensed deck officer on the navigation bridge

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114 UNITED STATES v. LOCKE
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who is capable of clearly understanding English.” The stat-
ute may not be supplemented by laws enacted by the States
without compromising the uniformity the federal rule itself
achieves.
The third Washington rule we find invalid under field pre-
emption is a navigation watch requirement in WAC § 317–21–
200; see also Appendix, infra, at 118. Washington has dif-
ferent rules for navigation watch, depending on whether
the tanker is operating in restricted visibility or not. We
mention the restricted visibility rule below, but now evaluate
the requirement which applies in general terms and reads:
“[T]he navigation watch shall consist of at least two licensed
deck officers, a helmsman, and a lookout.” The general
watch requirement is not tied to the peculiarities of Puget
Sound; it applies throughout Washington’s waters and at all
times. It is a general operating requirement and is pre-
empted as an attempt to regulate a tanker’s “operation” and
“manning” under 46 U. S. C. § 3703(a).
We have illustrated field pre-emption under § 3703(a) by
discussing three of Washington’s rules which, under the cur-
rent state of the record, we can determine cannot be en-
forced due to the assertion of federal authority found in that
section. The parties discuss other federal statutory pro-
visions and international agreements which also govern
specific aspects of international maritime commerce. In ap-
propriate circumstances, these also may have pre-emptive
effect.
For example, the record before us reveals that a fourth
state rule cannot stand in light of other sources of federal
regulation of the same subject. Washington requires ves-
sels that ultimately reach its waters to report certain marine
casualties. WAC § 317–21–130; see also Appendix, infra, at
117–118. The requirement applies to incidents (defined as
a “collision,” “allision,” “near-miss incident,” “marine cas-
ualty” of listed kinds, “accidental or intentional grounding,”
“failure of the propulsion or primary steering systems,”

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“failure of a component or control system,” “fire, flood, or
other incident that affects the vessel’s seaworthiness,” and
“spills of oil”), regardless of where in the world they might
have occurred. A vessel operator is required by the state
regulation to make a detailed report to the State on each
incident, listing the date, location, and weather conditions.
The report must also list the government agencies to whom
the event was reported and must contain a “brief analysis of
any known causes” and a “description of measures taken to
prevent a reoccurrence.” WAC § 317–21–130.
The State contends that its requirement is not pre-empted
because it is similar to federal requirements. This is an in-
correct statement of the law. It is not always a sufficient
answer to a claim of pre-emption to say that state rules sup-
plement, or even mirror, federal requirements. The Court
observed this principle when Commerce Clause doctrine was
beginning to take shape, holding in Sinnot v. Davenport, 22
How. 227 (1859), that Alabama could not require vessel own-
ers to provide certain information as a condition of operating
in state waters even though federal law also required the
owner of the vessel “to furnish, under oath, . . . all the infor-
mation required by this State law.” Id., at 242. The appro-
priate inquiry still remains whether the purposes and objec-
tives of the federal statutes, including the intent to establish
a workable, uniform system, are consistent with concurrent
state regulation. On this point, Justice Holmes’ later obser-
vation is relevant: “When Congress has taken the particular
subject-matter in hand coincidence is as ineffective as opposi-
tion, and a state law is not to be declared a help because it
attempts to go farther than Congress has seen fit to go.”
Charleston & Western Carolina R. Co. v. Varnville Furni-
ture Co., 237 U. S. 597, 604 (1915).
We hold that Congress intended that the Coast Guard reg-
ulations be the sole source of a vessel’s reporting obligations
with respect to the matters covered by the challenged state
statute. Under 46 U. S. C. § 6101, the Coast Guard “shall

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Opinion of the Court
prescribe regulations on the marine casualties to be reported
and the manner of reporting,” and the statute lists the kinds
of casualties that the regulations must cover. See also
§ 3717(a)(4) (requiring the Secretary of Transportation to
“establish a marine safety information system”). Congress
did not intend its reporting obligations to be cumulative to
those enacted by each political subdivision whose jurisdiction
a vessel enters. The State’s reporting requirement is a sig-
nificant burden in terms of cost and the risk of innocent non-
compliance. The Roanoke, 189 U. S. 185, 195 (1903) (the
master of a vessel is in a position “such that it is almost
impossible for him to acquaint himself with the laws of each
individual State he may visit”). Furthermore, it affects a
vessel operator’s out-of-state obligations and conduct, where
a State’s jurisdiction and authority are most in doubt. The
state reporting requirement under WAC § 317–21–130 is
pre-empted.
V
As to conflict pre-emption under Title I, Washington ar-
gues that certain of its regulations, such as its watch require-
ment in times of restricted visibility, are of limited extrater-
ritorial effect and necessary to address the peculiarities of
Puget Sound. On remand, the Court of Appeals or District
Court should consider whether the remaining regulations
are pre-empted under Title I conflict pre-emption or Title II
field pre-emption, or are otherwise pre-empted by these
titles or under any other federal law or international agree-
ment raised as possible sources of pre-emption.
We have determined that Washington’s regulations re-
garding general navigation watch procedures, English lan-
guage skills, training, and casualty reporting are pre-
empted. Petitioners make substantial arguments that the
remaining regulations are pre-empted as well. It is prefera-
ble that the remaining claims be considered by the Court of
Appeals or by the District Court within the framework we
have discussed. The United States did not participate in

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117 Cite as: 529 U. S. 89 (2000)
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these cases until appeal. Resolution of these cases would
benefit from the development of a full record by all inter-
ested parties.
We infer from the record that Washington is not now en-
forcing its regulations. If, pending adjudication of these
cases on remand, a threat of enforcement emerges, the Court
of Appeals or the District Court would weigh any application
for stay under the appropriate legal standards in light of
the principles we have discussed and with recognition of the
national interests at stake.
When one contemplates the weight and immense mass of
oil ever in transit by tankers, the oil’s proximity to coastal
life, and its destructive power even if a spill occurs far upon
the open sea, international, federal, and state regulation may
be insufficient protection. Sufficiency, however, is not the
question before us. The issue is not adequate regulation but
political responsibility; and it is, in large measure, for Con-
gress and the Coast Guard to confront whether their regula-
tory scheme, which demands a high degree of uniformity, is
adequate. States, as well as environmental groups and local
port authorities, will participate in the process. See 46
U. S. C. § 3703(a) (requiring the Coast Guard to consider the
views of “officials of State and local governments,” “rep-
resentative of port and harbor authorities,” and “repre-
sentatives of environmental groups” in arriving at national
standards).
The judgment of the Court of Appeals is reversed, and
these cases are remanded for further proceedings consistent
with this opinion.
It is so ordered.
APPENDIX TO OPINION OF THE COURT
“1. Event Reporting—WAC 317–21–130. Requires opera-
tors to report all events such as collisions, allisions and
near-miss incidents for the five years preceding filing of a

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118 UNITED STATES v. LOCKE
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prevention plan, and all events that occur thereafter for
tankers that operate in Puget Sound.
“2. Operating Procedures—Watch Practices—[WAC 317–
21–200]. Requires tankers to employ specific watch and
lookout practices while navigating and when at anchor, and
requires a bridge resource management system that is the
‘standard practice throughout the owner’s or operator’s
fleet,’ and which organizes responsibilities and coordinates
communication between members of the bridge.
“3. Operating Procedures—Navigation—WAC 317–21–
205. Requires tankers in navigation in state waters to re-
cord positions every fifteen minutes, to write a comprehen-
sive voyage plan before entering state waters, and to make
frequent compass checks while under way.
“4. Operating Procedures—Engineering—WAC 317–21–
210. Requires tankers in state waters to follow specified
engineering and monitoring practices.
“5. Operating Procedures—Prearrival Tests and Inspec-
tions—WAC 317–21–215. Requires tankers to undergo a
number of tests and inspections of engineering, navigation
and propulsion systems twelve hours or less before entering
or getting underway in state waters.
“6. Operating Procedures—Emergency Procedures—
WAC 317–21–220. Requires tanker masters to post written
crew assignments and procedures for a number of ship-
board emergencies.
“7. Operating Procedures—Events—WAC 317–21–225.
Requires that when an event transpires in state waters, such
as a collision, allision or near-miss incident, the operator is
prohibited from erasing, discarding or altering the position
plotting records and the comprehensive written voyage plan.
“8. Personnel Policies—Training—WAC 317–21–230. Re-
quires operators to provide a comprehensive training pro-
gram for personnel that goes beyond that necessary to obtain
a license or merchant marine document, and which includes
instructions on a number of specific procedures.

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“9. Personnel Policies—Illicit Drugs and Alcohol Use—
WAC 317–21–235. Requires drug and alcohol testing and
reporting.
“10. Personnel Policies—Personnel Evaluation—WAC
317–21–240. Requires operators to monitor the fitness for
duty of crew members, and requires operators to at least
annually provide a job performance and safety evaluation for
all crew members on vessels covered by a prevention plan
who serve for more than six months in a year.
“11. Personnel Policies—Work Hours—WAC 317–21–245.
Sets limitations on the number of hours crew members may
work.
“12. Personnel Policies—Language—WAC 317–21–250.
Requires all licensed deck officers and the vessel master to
be proficient in English and to speak a language understood
by subordinate officers and unlicensed crew. Also requires
all written instruction to be printed in a language under-
stood by the licensed officers and unlicensed crew.
“13. Personnel Policies—Record Keeping—WAC 317–21–
255. Requires operators to maintain training records for
crew members assigned to vessels covered by a prevention
plan.
“14. Management—WAC 317–21–260. Requires opera-
tors to implement management practices that demonstrate
active monitoring of vessel operations and maintenance, per-
sonnel training, development, and fitness, and technological
improvements in navigation.
“15. Technology—WAC 317–21–265. Requires tankers to
be equipped with global positioning system receivers, two
separate radar systems, and an emergency towing system.
“16. Advance Notice of Entry and Safety Reports—WAC
317–21–540. Requires at least twenty-four hours notice
prior to entry of a tanker into state waters, and requires
that the notice report any conditions that pose a hazard to
the vessel or the marine environment.” 148 F. 3d, at 1057–
1058 (footnote omitted).