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, Wash-ington, 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

Nos. 93–762 and 93–1094

JEROME B. GRUBART, INC., PETITIONER

93–762	v.

GREAT LAKES DREDGE & DOCK

COMPANY et al.

CITY OF CHICAGO, PETITIONER

93–1094	v.

GREAT LAKES DREDGE & DOCK

COMPANY et al.

on writs of certiorari to the united states court of appeals for the seventh circuit

[February 22, 1995]

Justice Souter delivered the opinion of the Court.

On April 13, 1992, water from the Chicago River poured into a freight tunnel running under the river and thence into the basements of buildings in the downtown Chicago Loop. Allegedly, the flooding resulted from events several months earlier, when the respondent Great Lakes Dredge and Dock Company had used a crane, sitting on a barge in the river next to a bridge, to drive piles into the river bed above the tunnel. The issue before us is whether a court of the United States has admiralty jurisdiction to determine and limit the extent of Great Lakes's tort liability. We hold the case to be within federal admiralty jurisdiction.

The complaint, together with affidavits subject to no objection, alleges the following facts. In 1990, Great Lakes bid on a contract with the petitioner city of Chicago to replace wooden pilings clustered around the piers of several bridges spanning the Chicago River, a navigable waterway within the meaning of The Daniel Ball, 10 Wall. 557, 563 (1871). See Escanaba Co. v. Chicago, 107 U. S. 678, 683 (1883). The pilings (called dolphins) keep ships from bumping into the piers and so protect both. After winning the contract, Great Lakes carried out the work with two barges towed by a tug. One barge carried pilings; the other carried a crane that pulled out old pilings and helped drive in new ones.

In August and September 1991, Great Lakes replaced the pilings around the piers projecting into the river and supporting the Kinzie Street Bridge. After towing the crane-carrying barge into position near one of the piers, Great Lakes's employees secured the barge to the river bed with spuds, or long metal legs that project down from the barge and anchor it. The workers then used the crane on the barge to pull up old pilings, stow them on the other barge, and drive new pilings into the river bed around the piers. About seven months later, an eddy formed in the river near the bridge as the collapsing walls or ceiling of a freight tunnel running under the river opened the tunnel to river water, which flowed through to flood buildings in the Loop.

After the flood, many of the victims brought actions in state court against Great Lakes and the city of Chicago, claiming that in the course of replacing the pilings Great Lakes had negligently weakened the tunnel structure, which Chicago (its owner) had not properly maintained. Great Lakes then brought this lawsuit in the United States District Court, invoking federal admiralty jurisdiction. Count I of the complaint seeks the protection of the Limitation of Vessel Owner's Liability Act (Limitation Act), 46 U. S. C. App. §181 et seq., a statute that would, in effect, permit the admiralty court to decide whether Great Lakes committed a tort and, if so, to limit Great Lakes's liability to the value of the vessels (the tug and two barges) involved if the tort was committed "without the privity or knowledge" of the vessels' owner, 46 U. S. C. App. §183(a). Counts II and III of Great Lakes's complaint ask for indemnity and contribution from the city for any resulting loss to Great Lakes.

The city, joined by petitioner Jerome B. Grubart, Inc., one of the state-court plaintiffs, filed a motion to dismiss this suit for lack of admiralty jurisdiction. Fed. Rule Civ. Proc. 12(b)(1). The District Court granted the motion, the Seventh Circuit reversed, Great Lakes Dredge & Dock Co. v. Chicago, 3 F. 3d 225 (1993), and we granted certiorari, 510 U. S. ___ (1994). We now affirm.

The parties do not dispute the Seventh Circuit's conclusion that jurisdiction as to Counts II and III (indemnity and contribution) hinges on jurisdiction over the Count I claim. See 3 F. 3d, at 231, n. 9; see also 28 U. S. C. §1367 (1988 ed., Supp. V) (supplemental jurisdiction); Fed. Rules Civ. Proc. 14(a) and (c) (impleader of third parties). Thus, the issue is simply whether or not a federal admiralty court has jurisdiction over claims that Great Lakes's faulty replacement work caused the flood damage.

A federal court's authority to hear cases in admiralty flows initially from the Constitution, which "extend[s]" federal judicial power "to all Cases of admiralty and maritime Jurisdiction." U. S. Const., Art. III, §2. Congress has embodied that power in a statute giving federal district courts "original jurisdiction . . . of . . . [a]ny civil case of admiralty or maritime jurisdic tion. . . ." 28 U. S. C. §1333(1).

The traditional test for admiralty tort jurisdiction asked only whether the tort occurred on navigable waters. If it did, admiralty jurisdiction followed; if it did not, admiralty jurisdiction did not exist. See, e.g., Thomas v. Lane, 23 F. Cas. 957, 960 (No. 13902) (CC Me. 1813) (Story, J., on Circuit). This ostensibly simple locality test was complicated by the rule that the injury had to be "wholly" sustained on navigable waters for the tort to be within admiralty. The Plymouth, 3 Wall. 20, 34 (1866) (no jurisdiction over tort action brought by the owner of warehouse destroyed in a fire that started on board a ship docked nearby). Thus, admiralty courts lacked jurisdiction over, say, a claim following a ship's collision with a pier insofar as it injured the pier, for admiralty law treated the pier as an extension of the land. Martin v. West, 222 U. S. 191, 197 (1911); Cleveland T. & V. R. Co. v. Cleveland S. S. Co., 208 U. S. 316, 319 (1908).

This latter rule was changed in 1948, however, when Congress enacted the Extension of Admiralty Jurisdiction Act, 62 Stat. 496. The Act provided that

"[t]he admiralty and maritime jurisdiction of the United States shall extend to and include all cases of damage or injury, to person or property, caused by a vessel on navigable water, notwithstanding that such damage or injury be done or consummated on land." 46 U. S. C. App. §740.

The purpose of the Act was to end concern over the sometimes confusing line between land and water, by investing admiralty with jurisdiction over "all cases" where the injury was caused by a ship or other vessel on navigable water, even if such injury occurred on land. See, e.g., Gutierrez v. Waterman S. S. Corp., 373 U. S. 206, 209–210 (1963); Executive Jet Aviation, Inc. v. City of Cleveland, 409 U. S. 249, 260 (1972).

After this congressional modification to gather the odd case into admiralty, the jurisdictional rule was qualified again in three decisions of this Court aimed at keeping a different class of odd cases out. In the first case, Executive Jet, supra, tort claims arose out of the wreck of an airplane that collided with a flock of birds just after take-off on a domestic flight and fell into the navigable waters of Lake Erie. We held that admiralty lacked jurisdiction to consider the claims. We wrote that "a purely mechanical application of the locality test" was not always "sensible" or "consonant with the purposes of maritime law," id., at 261, as when (for example) the literal and universal application of the locality rule would require admiralty courts to adjudicate tort disputes between colliding swimmers, id., at 255. We held that "claims arising from airplane accidents are not cognizable in admiralty" despite the location of the harm, unless the "the wrong bear[s] a significant relationship to traditional maritime activity." Id., at 268.

The second decision, Foremost Ins. Co. v. Richardson, 457 U. S. 668 (1982), dealt with tort claims arising out of the collision of two pleasure boats in a navigable river estuary. We held that admiralty courts had jurisdiction, id., at 677, even though jurisdiction existed only if "the wrong" had "a significant connection with traditional maritime activity," id., at 674. We conceded that pleasure boats themselves had little to do with the maritime commerce lying at the heart of the admiralty court's basic work, id., at 674–675, but we nonetheless found the necessary relationship in

"[t]he potential disruptive impact [upon maritime commerce] of a collision between boats on navigable waters, when coupled with the traditional concern that admiralty law holds for navigation . . . ." Id., at 675.

In the most recent of the trilogy, Sisson v. Ruby, 497 U. S. 358 (1990), we held that a federal admiralty court had jurisdiction over tort claims arising when a fire, caused by a defective washer/dryer aboard a pleasure boat docked at a marina, burned the boat, other boats docked nearby, and the marina itself. Id., at 367. We elaborated on the enquiry exemplified in Executive Jet and Foremost by focusing on two points to determine the relationship of a claim to the objectives of admiralty jurisdiction. We noted, first, that the incident causing the harm, the burning of docked boats at a marina on navigable waters, was of a sort "likely to disrupt [maritime] commercial activity." Id., at 363. Second, we found a "substantial relationship" with "traditional maritime activity" in the kind of activity from which the incident arose, "the storage and maintenance of a vessel . . . on navigable waters." Id., at 365–367.

After Sisson, then, a party seeking to invoke federal admiralty jurisdiction pursuant to 28 U. S. C. §1333(1) over a tort claim must satisfy conditions both of location and of connection with maritime activity. A court applying the location test must determine whether the tort occurred on navigable water or whether injury suffered on land was caused by a vessel on navigable water. 46 U. S. C. App. §740. The connection test raises two issues. A court, first, must "assess the general features of the type of incident involved," 497 U. S., at 363, to determine whether the incident has "a potentially disruptive impact on maritime commerce," id., at 364, n. 2. Second, a court must determine whether "the general character" of the "activity giving rise to the incident" shows a "substantial relationship to traditional maritime activity." Id., at 365, 364, and n. 2. We now apply the tests to the facts of this case.

The location test is, of course, readily satisfied. If Great Lakes caused the flood, it must have done so by weakening the structure of the tunnel while it drove in new pilings or removed old ones around the bridge piers. The weakening presumably took place as Great Lakes's workers lifted and replaced the pilings with a crane that sat on a barge stationed in the Chicago River. The place in the river where the barge sat, and from which workers directed the crane, is in the "navigable waters of the United States." Escanaba Co., 107 U. S., at 683. Thus, if Great Lakes committed a tort, it must have done it while on navigable waters.

It must also have done it "by a vessel." Even though the barge was fastened to the river bottom and was in use as a work platform at the times in question, at other times it was used for transportation. See 3 F. 3d, at 229. Petitioners do not here seriously dispute the conclusion of each court below that the Great Lakes barge is, for admiralty tort purposes, a "vessel." The fact that the pile-driving was done with a crane makes no difference under the location test, given the maritime law that ordinarily treats an "appurtenance" attached to a vessel in navigable waters as part of the vessel itself. See, e.g., Victory Carriers, Inc. v. Law, 404 U. S. 202, 210–211 (1971); Gutierrez, 373 U. S., at 209–210.

Because the injuries suffered by Grubart and the other flood victims were caused by a vessel on navigable water, the location enquiry would seem to be at an end, "notwithstanding that such damage or injury [have been] done or consummated on land." 46 U. S. C. App. §740. Both Grubart and Chicago nonetheless ask us to subject the Extension Act to limitations not apparent from its text. While they concede that the Act refers to "all cases of damage or injury," they argue that "all" must not mean literally every such case, no matter how great the distance between the vessel's tortious activity and the resulting harm. They contend that, to be within the Act, the damage must be close in time and space to the activity that caused it: that it must occur "reasonably contemporaneously" with the negligent conduct and no "farther from navigable waters than the reach of the vessel, its appurtenances and cargo." For authority, they point to this Court's statement in Gutierrez, supra, that jurisdiction is present when the "impact" of the tortious activity "is felt ashore at a time and place not remote from the wrongful act." Id., at 210.

The demerits of this argument lie not only in its want of textual support for its nonremoteness rule, but in its disregard of a less stringent but familiar proximity condition tied to the language of the statute. The Act uses the phrase "caused by," which more than one Court of Appeals has read as requiring what tort law has traditionally called "proximate causation." See, e.g., Pryor v. American President Lines, 520 F. 2d 974, 979 (CA4 1975), cert. denied, 423 U. S. 1055 (1976); Adams v. Harris County, 452 F. 2d 994, 996–997 (CA5 1971), cert. denied, 406 U. S. 968 (1972). This classic tort notion normally eliminates the bizarre, cf. Palsgraf v. Long Island R. Co., 248 N.Y. 339, 162 N. E. 99 (1928), and its use should obviate not only the complication but even the need for further temporal or spatial limitations. Nor is reliance on familiar proximate causation inconsistent with Gutierrez, which used its nonremote language, not to announce a special test, but simply to distinguish its own facts (the victim having slipped on beans spilling from cargo containers being unloaded from a ship) from what the Court called "[v]arious far-fetched hypotheticals," such as injury to someone slipping on beans that continue to leak from the containers after they had been shipped from Puerto Rico to a warehouse in Denver. 373 U. S., at 210. See also Victory Carriers, supra, at 210–211.

The city responds by saying that, as a practical matter, the use of proximate cause as a limiting jurisdictional principle would undesirably force an admiralty court to investigate the merits of the dispute at the outset of a case when it determined jurisdiction. The argument, of course, assumes that the truth of jurisdictional allegations must always be determined with finality at the threshold of litigation, but that assumption is erroneous. Normal practice permits a party to establish jurisdiction at the outset of a case by means of a nonfrivolous assertion of jurisdictional elements, see, e.g., Bray v. Alexandria Women's Health Clinic, 506 U. S. ___, ___ (1993) (slip op., at 21); Bell v. Hood, 327 U. S. 678, 682–683 (1946), and any litigation of a contested subject-matter jurisdictional fact issue occurs in comparatively summary procedure before a judge alone (as distinct from litigation of the same fact issue as an element of the cause of action, if the claim survives the jurisdictional objection). See 2A J. Moore & J. Lucas, Moore's Federal Practice ¶12.07[2.—1] (2d ed. 1994); 5A C. Wright & A. Miller, Federal Practice and Procedure §1350 (2d ed. 1990). There is no reason why this should not be just as true for proximate causation as it is for the maritime nature of the tortfeasor's activity giving rise to the incident. See Sisson, 497 U. S., at 365. There is no need or justification, then, for imposing an additional nonremoteness hurdle in the name of jurisdiction.

We now turn to the maritime connection enquiries, the first being whether the incident involved was of a sort with the potential to disrupt maritime commerce. In Sisson, we described the features of the incident in general terms as "a fire on a vessel docked at a marina on navigable waters," id., at 363, and determined that such an incident "plainly satisf[ied]" the first maritime connection requirement, ibid., because the fire could have "spread to nearby commercial vessels or ma[d]e the marina inaccessible to such vessels" and therefore "[c]ertainly" had a "potentially disruptive impact on maritime commerce." Id., at 362. We noted that this first prong went to potential effects, not to the "particular facts of the incident," noting that in both Executive Jet and Foremost we had focused not on the specific facts at hand but on whether the "general features" of the incident were "likely to disrupt commercial activity." 497 U. S., at 363.

The first Sisson test turns, then, on a description of the incident at an intermediate level of possible generality. To speak of the incident as "fire" would have been too general to differentiate cases; at the other extreme, to have described the fire as damaging nothing but pleasure boats and their tie-up facilities would have ignored, among other things, the capacity of pleasure boats to endanger commercial shipping that happened to be nearby. We rejected both extremes and instead asked whether the incident could be seen within a class of incidents that posed more than a fanciful risk to commercial shipping.

Following Sisson, the "general features" of the incident at issue here may be described as damage by a vessel in navigable water to an underwater structure. So characterized, there is little question that this is the kind of incident that has a "potentially disruptive impact on maritime commerce." As it actually turned out in this case, damaging a structure beneath the river bed could lead to a disruption in the water course itself, App. 33 (eddy formed above the leak); and, again as it actually happened, damaging a structure so situated could lead to restrictions on the navigational use of the waterway during required repairs. See Pet. for Cert. in No. 93–1094, p. 22a (District Court found that after the flood "[t]he river remained closed for over a month," "[r]iver traffic ceased, several commuter ferries were stranded, and many barges could not enter the river system . . . because the river level was lowered to aid repair efforts"). Cf. Pennzoil Producing Co. v. Offshore Express, Inc., 943 F. 2d 1465 (CA5 1991) (admiralty suit when vessel struck and ruptured gas pipeline and gas exploded); Marathon Pipe Line Co. v. Drilling Rig Rowan/Odessa, 761 F. 2d 229, 233 (CA5 1985) (admiralty jurisdiction when vessel struck pipeline, "a fixed structure on the seabed"); Orange Beach Water, Sewer, and Fire Protection Authority v. M/V Alva, 680 F. 2d 1374 (CA11 1982) (admiralty suit when vessel struck underwater pipeline).

In the second Sisson enquiry, we look to whether the general character of the activity giving rise to the incident shows a substantial relationship to traditional maritime activity. We ask whether a tortfeasor's activity, commercial or noncommercial, on navigable waters is so closely related to activity traditionally subject to admiralty law that the reasons for applying special admiralty rules would apply in the case at hand. Navigation of boats in navigable waters clearly falls within the substantial relationship, Foremost, 457 U. S., at 675; storing them at a marina on navigable waters is close enough, Sisson, supra, at 367; whereas in flying an airplane over the water, Executive Jet, 409 U. S., at 270–271, as in swimming, id., at 255–256, the relationship is too attenuated.

On like reasoning, the "activity giving rise to the incident" in this case, Sisson, supra, at 364, should be characterized as repair or maintenance work on a navigable waterway performed from a vessel. Described in this way, there is no question that the activity is substantially related to traditional maritime activity, for barges and similar vessels have traditionally been engaged in repair work similar to what Great Lakes contracted to perform here. See, e.g., Shea v. Rev-Lyn Contracting Co., 868 F. 2d 515, 518 (CA1 1989) (bridge repair by crane-carrying barge); Nelson v. United States, 639 F. 2d 469, 472 (CA9 1980) (Kennedy, J.) (repair of wave suppressor from a barge); In re New York Dock Co., 61 F. 2d 777 (CA2 1932) (pile driving from crane-carrying barge in connection with the building of a dock); In re P. Sanford Ross, Inc., 196 F. 921, 923–924 (EDNY 1912) (pile driving from crane-carrying barge close to water's edge), rev'd on other grounds, 204 F. 248 (CA2 1913); cf. In re The V-14813, 65 F. 2d 789, 790 (CA5 1933) ("[t]here are many cases holding that a dredge, or a barge with a pile driver, employed on navigable waters, is subject to maritime jurisdiction"); Lawrence v. Flatboat, 84 F. 200 (SD Ala. 1897) (pile driving from crane-carrying barge in connection with the erection of bulkheads), aff'd sub nom. Southern Log Cart & Supply Co. v. Lawrence, 86 F. 907 (CA5 1898).

The city argues, to the contrary, that a proper application of the activity prong of Sisson would consider the city's own alleged failure at properly maintaining and operating the tunnel system that runs under the river. City Brief 48–49. If this asserted proximate cause of the flood victims' injuries were considered, the city submits, its failure to resemble any traditional maritime activity would take this case out of admiralty.

The city misreads Sisson, however, which did not consider the activities of the washer/dryer manufacturer, who was possibly an additional tortfeasor, and whose activities were hardly maritime; the activities of Sisson, the boat owner, supplied the necessary substantial relationship to traditional maritime activity. Likewise, in Foremost, we said that "[b]ecause the `wrong' here involves the negligent operation of a vessel on navigable waters, we believe that it has a sufficient nexus to traditional maritime activity to sustain admiralty jurisdiction . . . ." 457 U. S., at 674. By using the word "involves," we made it clear that we need to look only to whether one of the arguably proximate causes of the incident originated in the maritime activity of a tortfeasor: as long as one of the putative tortfeasors was engaged in traditional maritime activity the allegedly wrongful activity will "involve" such traditional maritime activity and will meet the second nexus prong. Thus, even if we were to identify the "activity giving rise to the incident" as including the acts of the city as well as Great Lakes, admiralty jurisdiction would nevertheless attach. That result would be true to Sisson's requirement of a "substantial relationship" between the "activity giving rise to the incident" and traditional maritime activity. Sisson did not require, as the city in effect asserts, that there be a complete identity between the two. The substantial relationship test is satisfied when at least one alleged tortfeasor was engaging in activity substantially related to traditional maritime activity and such activity is claimed to have been a proximate cause of the incident.

Petitioners also argue that we might get a different result simply by characterizing the "activity" in question at a different level of generality, perhaps as "repair and maintenance," or, as "pile driving near a bridge." The city is, of course, correct that a tortfeasor's activity can be described at a sufficiently high level of generality to eliminate any hint of maritime connection, and if that were properly done Sisson would bar assertion of admiralty jurisdiction. But to suggest that such hyper-generalization ought to be the rule would convert Sisson into a vehicle for eliminating admiralty jurisdiction. Although there is inevitably some play in the joints in selecting the right level of generality when applying the Sisson test, the inevitable imprecision is not an excuse for whimsy. The test turns on the comparison of traditional maritime activity to the arguably maritime character of the tortfeasor's activity in a given case; the comparison would merely be frustrated by eliminating the maritime aspect of the tortfeasor's activity from consideration.

Grubart makes an additional claim that Sisson is being given too expansive a reading. If the activity at issue here is considered maritime-related, it argues, then virtually "every activity involving a vessel on navigable waters" would be "a traditional maritime activity sufficient to invoke maritime jurisdiction." Grubart Brief 6. But this is not fatal criticism. This Court has not proposed any radical alteration of the traditional criteria for invoking admiralty jurisdiction in tort cases, but has simply followed the lead of the lower federal courts in rejecting a location rule so rigid as to extend admiralty to a case involving an airplane, not a vessel, engaged in an activity far removed from anything traditionally maritime. See Executive Jet, 409 U. S., at 268–274; see also Peytavin v. Government Employees Ins. Co., 453 F. 2d 1121, 1127 (CA5 1972) (no jurisdiction over claim for personal injury by motorist who was rear-ended while waiting for a ferry on a floating pontoon serving as the ferry's landing); Chapman v. Grosse Pointe Farms, 385 F. 2d 962 (CA6 1967) (no admiralty jurisdiction over claim of swimmer who injured himself when diving off pier into shallow but navigable water). In the cases after Executive Jet, the Court stressed the need for a maritime connection, but found one in the navigation or berthing of pleasure boats, despite the facts that the pleasure boat activity took place near shore, where States have a strong interest in applying their own tort law, or was not on all fours with the maritime shipping and commerce that has traditionally made up the business of most maritime courts. Sisson, 497 U. S., at 367; Foremost, 457 U. S., at 675. Although we agree with petitioners that these cases do not say that every tort involving a vessel on navigable waters falls within the scope of admiralty jurisdiction no matter what, they do show that ordinarily that will be so.

Perhaps recognizing the difficulty of escaping the case law, petitioners ask us to change it. In cases "involving land based parties and injuries," the city would have us adopt a condition of jurisdiction that

"the totality of the circumstances reflects a federal interest in protecting maritime commerce sufficiently weighty to justify shifting what would otherwise be state-court litigation into federal court under the federal law of admiralty." City Brief 32.

Grubart and the city say that the Fifth Circuit has applied a somewhat similar "four-factor test" looking to "the functions and roles of the parties; the types of vehicles and instrumentalities involved; the causation and the type of injury; and traditional concepts of the role of admiralty law." Kelly v. Smith, 485 F. 2d 520, 525 (CA5 1973); see also Molett v. Penrod Drilling Co., 826 F. 2d 1419, 1426 (CA5 1987) (adding three more factors: the "impact of the event on maritime shipping and commerce"; "the desirability of a uniform national rule to apply to such matters"; and "the need for admiralty `expertise' in the trial and decision of the case"), cert. denied sub nom. Columbus-McKinnon, Inc. v. Gearench, Inc., 493 U. S. 1003 (1989). Although they point out that Sisson disapproved the use of four-factor or seven-factor tests "where all the relevant entities are engaged in similar types of activity," this rule implicitly left the matter open for cases like this one, where most of the victims, and one of the tortfeasors, are based on land. See 497 U. S., at 365, n. 3 ("Different issues may be raised by a case in which one of the instrumentalities is engaged in a traditional maritime activity, but the other is not"). The city argues that there is a good reason why cases like this one should get different treatment. Since the basic rationale for federal admiralty jurisdiction is "protection of maritime commerce through uniform rules of decision," the proposed jurisdictional test would improve on Sisson in limiting the scope of admiralty jurisdiction more exactly to its rationale. A multiple factor test would minimize, if not eliminate, the awkward possibility that federal admiralty rules or procedures will govern a case, to the disadvantage of state law, when admiralty's purpose does not require it. Cf. Foremost, supra, at 677–686 (Powell, J., dissenting).

Although the arguments are not frivolous, they do not persuade. It is worth recalling that the Sisson tests are aimed at the same objectives invoked to support a new multifactor test, the elimination of admiralty jurisdiction where the rationale for the jurisdiction does not support it. If the tort produces no potential threat to maritime commerce or occurs during activity lacking a substantial relationship to traditional maritime activity, Sisson assumes that the objectives of admiralty jurisdiction probably do not require its exercise, even if the location test is satisfied. If, however, the Sisson tests are also satisfied, it is not apparent why the need for admiralty jurisdiction in aid of maritime commerce somehow becomes less acute merely because land-based parties happen to be involved. Certainly Congress did not think a land-based party necessarily diluted the need for admiralty jurisdiction or it would have kept its hands off the primitive location test.

Of course one could claim it to be odd that under Sisson a land-based party (or more than one) may be subject to admiralty jurisdiction, but it would appear no less odd under the city's test that a maritime tortfeasor in the most traditional mould might be subject to state common-law jurisdiction. Other things being equal, it is not evident why the first supposed anomaly is worse than the second. But other things are not even equal. As noted just above, Congress has already made the judgment, in the Extension Act, that a land-based victim may properly be subject to admiralty jurisdiction. Surely a land-based joint tortfeasor has no claim to supposedly more favorable treatment.

Nor are these the only objections to the city's position. Contrary to what the city suggests, City Brief 10, 14–15, 25–26, 30, exercise of federal admiralty jurisdiction does not result in automatic displacement of state law. It is true that, "[w]ith admiralty jurisdiction comes the application of substantive admiralty law." East River S. S. Corp. v. Transamerica DeLaval Inc., 476 U. S. 858, 864 (1986). But, to characterize that law, as the city apparently does, as "federal rules of decision," City Brief 15, is

"a destructive oversimplification of the highly intricate interplay of the States and the National Government in their regulation of maritime commerce. It is true that state law must yield to the needs of a uniform federal maritime law when this Court finds inroads on a harmonious system. But this limitation still leaves the States a wide scope." Romero v. International Terminal Operating Co., 358 U. S. 354, 373 (1959) (footnote omitted).

See East River, supra, at 864–865 ("Drawn from state and federal sources, the general maritime law is an amalgam of traditional common-law rules, modifications of those rules, and newly created rules" (footnote omitted)). Thus, the city's proposal to synchronize the jurisdictional enquiry with the test for determining the applicable substantive law would discard a fundamental feature of admiralty law, that federal admiralty courts sometimes do apply state law. See, e.g., American Dredging Co. v. Miller, 510 U. S. ___, ___ (1994) (slip op., at 7–8); see also 1 S. Friedell, Benedict on Admiralty § 112 p. 7–49 (7th ed. 1994).

Finally, on top of these objections going to the city's premises there is added a most powerful one based on the practical consequences of adopting a multifactor test. Although the existing case law tempers the locality test with the added requirements looking to potential harm and traditional activity, it reflects customary practice in seeing jurisdiction as the norm when the tort originates with a vessel in navigable waters, and in treating departure from the locality principle as the exception. For better or worse, the case law has thus carved out the approximate shape of admiralty jurisdiction in a way that admiralty lawyers understand reasonably well. As against this approach, so familiar and relatively easy, the proposed four- or seven-factor test would be hard to apply, jettisoning relative predictability for the open-ended rough-and-tumble of factors, inviting complex argument in a trial court and a virtually inevitable appeal.

Consider, for example, just one of the factors under the city's test, requiring a district court at the beginning of every purported admiralty case to determine the source (state or federal) of the applicable substantive law. The difficulty of doing that was an important reason why this Court in Romero, supra, was unable to hold that maritime claims fell within the scope of the federal-question-jurisdiction statute, 28 U. S. C. §1331. 358 U. S., at 375–376 ("sound judicial policy does not encourage a situation which necessitates constant adjudication of the boundaries of state and federal competence"). That concern applies just as strongly to cases invoking a district court's admiralty jurisdiction under 28 U. S. C. §1333, under which the jurisdictional enquiry for maritime torts has traditionally been quite uncomplicated.

Reasons of practice, then, are as weighty as reasons of theory for rejecting the city's call to adopt a multifactor test for admiralty jurisdiction for the benefit of land-based parties to a tort action.

Accordingly, we conclude that the Court of Appeals correctly held that the District Court had admiralty jurisdiction over the respondent's Limitation Act suit. The judgment of the Court of Appeals is

Affirmed.

Justice Stevens and Justice Breyer took no part in the decision of this case.