with whom Justice Powell, Justice O’Connor, and Justice Scalia join, dissenting.
More than 50 years ago, this Court determined the constitutionality of Pennsylvania’s Kohler Act as it affected the property interests of coal mine operators. Pennsylvania Coal Co. v. Mahon, 260 U. S. 393 (1922). The Bituminous Mine Subsidence and Land Conservation Act approved today effects an interference with such interests in a strikingly similar manner. The Court finds at least two reasons why this case is different. First, we are told, “the character of the governmental action involved here leans heavily against finding a taking.” Ante, at 485. Second, the Court concludes that the Subsidence Act neither “makes it impossible for peti*507tioners to profitably engage in their business,” nor involves “undue interference with [petitioners’] investment-backed expectations.” Ibid. Neither of these conclusions persuades me that this case is different, and I believe that the Subsidence Act works a taking of petitioners’ property interests. I therefore dissent.
1 — 4
In apparent recognition of the obstacles presented by Pennsylvania Coal to the decision it reaches, the Court attempts to undermine the authority of Justice Holmes’ opinion as to the validity of the Kohler Act, labeling it “uncharacteristically . . . advisory.” Ante, at 484. I would not so readily dismiss the precedential value of this opinion. There is, to be sure, some language in the case suggesting that it could have been decided simply by addressing the particular application of the Kohler Act at issue in the case. See, e. g., Pennsylvania Coal, supra, at 414 (“If we were called upon to deal with the plaintiffs’ position alone, we should think it clear that the statute does not disclose a public interest sufficient to warrant so extensive a destruction of the defendant’s constitutionally protected rights”). The Court, however, found that the validity of the Act itself was properly drawn into question: “[T]he case has been treated as one in which the general validity of the [Kohler] act should be discussed.” Ibid.1 The coal company clearly had an interest in obtaining a determination that the Kohler Act was unenforceable if it worked a taking without providing for compensation. For *508these reasons, I would not find the opinion of the Court in Pennsylvania Coal advisory in any respect.
The Court’s implication to the contrary is particularly disturbing in this context, because the holding in Pennsylvania Coal today discounted by the Court has for 65 years been the foundation of our “regulatory takings” jurisprudence. See Penn Central Transportation Co. v. New York City, 438 U. S. 104, 127 (1978); D. Hagman & J. Juergensmeyer, Urban Planning and Land Development Control Law 319 (2d ed. 1986) (“Pennsylvania Coal was a monumental decision which remains a vital element in contemporary taking law”). We have, for example, frequently relied on the admonition that “if regulation goes too far it will be recognized as a taking.” Pennsylvania Coal, supra, at 415. See, e. g., MacDonald, Sommer & Frates v. Yolo County, 477 U. S. 340, 348 (1986); Ruckelshaus v. Monsanto Co., 467 U. S. 986, 1003 (1984); PruneYard Shopping Center v. Robins, 447 U. S. 74, 83 (1980); Goldblatt v. Hempstead, 369 U. S. 590, 594 (1962); United States v. Central Eureka Mining Co., 357 U. S. 155, 168 (1958). Thus, even were I willing to assume that the opinion in Pennsylvania Coal standing alone is reasonably subject to an interpretation that renders more than half the discussion “advisory,” I would have no doubt that our repeated reliance on that opinion establishes it as a cornerstone of the jurisprudence of the Fifth Amendment’s Just Compensation Clause.
I accordingly approach this case with greater deference to the language as well as the holding of Pennsylvania Coal than does the Court. Admittedly, questions arising under the Just Compensation Clause rest on ad hoc factual inquiries, and must be decided on the facts and circumstances in each case. See Penn Central Transportation Co. v. New York City, supra, at 124; United States v. Central Eureka Mining Co., supra, at 168. Examination of the relevant factors presented here convinces me that the differences be*509tween them and those in Pennsylvania Coal verge on the trivial.
II
The Court first determines that this case is different from Pennsylvania Coal because “the Commonwealth of Pennsylvania has acted to arrest what it perceives to be a significant threat to the common welfare.” Ante, at 485. In my view, reliance on this factor represents both a misreading of Pennsylvania Coal and a misunderstanding of our precedents.
A
The Court opines that the decision in Pennsylvania Coal rested on the fact that the Kohler Act was “enacted solely for the benefit of private parties,” ante, at 486, and “served only private interests.” Ante, at 484. A review of the Kohler Act shows that these statements are incorrect. The Pennsylvania Legislature passed the statute “as remedial legislation, designed to cure existing evils and abuses.” Mahon v. Pennsylvania Coal Co., 274 Pa. 489, 495, 118 A. 491, 492 (1922) (quoting the Act). These were public “evils and abuses,” identified in the preamble as “wrecked and dangerous streets and highways, collapsed public buildings, churches, schools, factories, streets, and private dwellings, broken gas, water and sewer systems, the loss of human life . . . .” Id., at 496, 118 A., at 493.2 The Pennsylvania Supreme Court recognized that these concerns were “such as to create an emergency, properly warranting the exercise of the police power . . . .” Id., at 497, 118 A., at 493. There can be *510no doubt that the Kohler Act was intended to serve public interests.
Though several aspects of the Kohler Act limited its protection of these interests, see Pennsylvania Coal, 260 U. S., at 414, this Court did not ignore the public interests served by the Act. When considering the protection of the “single private house” owned by the Mahons, the Court noted that “[n]o doubt there is a public interest even in this.” Id., at 413 (emphasis added). It recognized that the Act “affects the mining of coal under streets or cities in places where the right to mine such coal has been reserved.” Id., at 414. See also id., at 416 (“We assume . . . that the statute was passed upon the conviction that an exigency existed that would warrant it, and we assume that an exigency exists that would warrant the exercise of eminent domain”). The strong public interest in the stability of streets and cities, however, was insufficient “to warrant achieving the desire by a shorter cut than the constitutional way of paying for the change.” Ibid. Thus, the Court made clear that the mere existence of a public purpose was insufficient to release the government from the compensation requirement: “The protection of private property in the Fifth Amendment presupposes that it is wanted for public use, but provides that it shall not be taken for such use without compensation.” Id., at 415.
The Subsidence Act rests on similar public purposes. These purposes were clearly stated by the legislature: “[T]o aid in the protection of the safety of the public, to enhance the value of [surface area] lands for taxation, to aid in the preservation of surface water drainage and public water supplies and generally to improve the use and enjoyment of such lands . . . .” Pa. Stat. Ann., Title 52, § 1406.2 (Purdon Supp. 1986). The Act’s declaration of policy states that mine subsidence “has seriously impeded land development . . . has caused a very clear and present danger to the health, safety and welfare of the people of Pennsylvania [and] erodes the *511tax base of the affected municipalities.” §§ 1406.3(2), (3), (4). The legislature determined that the prevention of subsidence would protect surface structures, advance the economic future and well-being of Pennsylvania, and ensure the safety and welfare of the Commonwealth’s residents. Ibid. Thus, it is clear that the Court has severely understated the similarity of purpose between the Subsidence Act and the Kohler Act. The public purposes in this case are not sufficient to distinguish it from Pennsylvania Coal.3
B
The similarity of the public purpose of the present Act to that in Pennsylvania Coal does not resolve the question whether a taking has occurred; the existence of such a public purpose is merely a necessary prerequisite to the government’s exercise of its taking power. See Hawaii Housing Authority v. Midkiff, 467 U. S. 229, 239-243, 245 (1984); Berman v. Parker, 348 U. S. 26, 32-33 (1954). The nature of these purposes may be relevant, for we have recognized that a taking does not occur where the government exercises its unquestioned authority to prevent a property owner from using his property to injure others without having to compensate the value of the forbidden use. See Goldblatt v. Hemp-*512stead, 369 U. S. 590 (1962); Hadacheck v. Sebastian, 239 U. S. 394 (1915); Mugler v. Kansas, 123 U. S. 623 (1887). See generally Penn Central Transportation Co. v. New York City, 438 U. S., at 144-146 (Rehnquist, J., dissenting). The Court today indicates that this “nuisance exception” alone might support its conclusion that no taking has occurred. Despite the Court’s implication to the contrary, see ante, at 485-486, and n. 15, the legitimacy of this purpose is a question of federal, rather than state, law, subject to independent scrutiny by this Court. This statute is not the type of regulation that our precedents have held to be within the “nuisance exception” to takings analysis.
The ease with which the Court moves from the recognition of public interests to the assertion that the activity here regulated is “akin to a public nuisance” suggests an exception far wider than recognized in our previous cases. “The nuisance exception to the taking guarantee,” however, “is not coterminous with the police power itself,” Penn Central Transportation, supra, at 145 (Rehnquist, J., dissenting), but is a narrow exception allowing the government to prevent “a misuse or illegal use.” Curtin v. Benson, 222 U. S. 78, 86 (1911). It is not intended to allow “the prevention of a legal and essential use, an attribute of its ownership.” Ibid.
The narrow nature of this exception is compelled by the concerns underlying the Fifth Amendment. Though, as the Court recognizes, ante, at 491-492, the Fifth Amendment does not prevent actions that secure a “reciprocity of advantage,” Pennsylvania Coal, supra, at 415, it is designed to prevent “the public from loading upon one individual more than his just share of the burdens of government, and says that when he surrenders to the public something more and different from that which is exacted from other members of the public, a full and just equivalent shall be returned to him.” Monongahela Navigation Co. v. United States, 148 U. S. 312, 325 (1893). See also Penn Central Transportation Co. v. New York City, supra, at 123-125; Armstrong v. *513United, States, 364 U. S. 40, 49 (1960). A broad exception to the operation of the Just Compensation Clause based on the exercise of multifaceted health, welfare, and safety regulations would surely allow government much greater authority than we have recognized to impose societal burdens on individual landowners, for nearly every action the government takes is intended to secure for the public an extra measure of “health, safety, and welfare.”
Thus, our cases applying the “nuisance” rationale have involved at least two narrowing principles. First, nuisance regulations exempted from the Fifth Amendment have rested on discrete and narrow purposes. See Goldblatt v. Hempstead, supra; Hadacheck v. Sebastian, supra; Mugler v. Kansas, supra. The Subsidence Act, however, is much more than a nuisance statute. The central purposes of the Act, though including public safety, reflect a concern for preservation of buildings, economic development, and maintenance of property values to sustain the Commonwealth’s tax base. We should hesitate to allow a regulation based on essentially economic concerns to be insulated from the dictates of the Fifth Amendment by labeling it nuisance regulation.
Second, and more significantly, our cases have never applied the nuisance exception to allow complete extinction of the value of a parcel of property. Though nuisance regulations have been sustained despite a substantial reduction in value, we have not accepted the proposition that the State may completely extinguish a property interest or prohibit all use without providing compensation. Thus, in Mugler v. Kansas, supra, the prohibition on manufacture and sale of intoxicating liquors made the distiller’s brewery “of little value” but did not completely extinguish the value of the building. Similarly, in Miller v. Schoene, 276 U. S. 272 (1928), the individual forced to cut down his cedar trees nevertheless was able “to use the felled trees.” Penn Central Transportation Co. v. New York City, supra, at 126. The *514restriction on surface mining upheld in Goldblatt v. Hempstead, supra, may have prohibited “a beneficial use” of the property, but did not reduce the value of the lot in question. 369 U. S., at 593, 594. In none of these cases did the regulation “destroy essential uses of private property.” Curtin v. Benson, supra, at 86.
Here, petitioners’ interests in particular coal deposits have been completely destroyed. By requiring that defined seams of coal remain in the ground, see ante, at 476-477, and n. 7, § 4 of the Subsidence Act has extinguished any interest one might want to acquire in this property, for “ ‘the right to coal consists in the right to mine it.’ ” Pennsylvania Coal, 260 U. S., at 414, quoting Commonwealth ex rel. Keator v. Clearview Coal Co., 256 Pa. 328, 331, 100 A. 820 (1917). Application of the nuisance exception in these circumstances would allow the State not merely to forbid one “particular use” of property with many uses but to extinguish all beneficial use of petitioners’ property.4
Though suggesting that the purposes alone are sufficient to uphold the Act, the Court avoids reliance on the nuisance exception by finding that the Subsidence Act does not impair petitioners’ investment-backed expectations or ability to profitably operate their businesses. This conclusion follows mainly from the Court’s broad definition of the “relevant mass of property,” ante, at 497, which allows it to ascribe to the Subsidence Act a less pernicious effect on the interests of the property owner. The need to consider the effect of regulation on some identifiable segment of property makes all important the admittedly difficult task of defining the relevant *515parcel. See Penn Central Transportation Co. v. New York City, 438 U. S., at 149, n. 13 (Rehnquist, J., dissenting). For the reasons explained below, I do not believe that the Court’s opinion adequately performs this task.
III
The Pennsylvania Coal Court found it sufficient that the Kohler Act rendered it “commercially impracticable to mine certain coal.” 260 U. S., at 414. The Court, ante, at 498, observes that this language is best understood as a conclusion that certain coal mines could not be operated at a profit. Petitioners have not at this stage of the litigation rested their claim on similar proof; they have not “claimed that their mining operations, or even any specific mines, have been unprofitable since the Subsidence Act was passed.” Ante, at 496. The parties have, however, stipulated for purposes of this facial challenge that the Subsidence Act requires petitioners to leave in the ground 27 million tons of coal, without compensation therefor. Petitioners also claim that the Act extinguishes their purchased interests in support estates which allow them to mine the coal without liability for subsidence. We are thus asked to consider whether these restrictions are such as to constitute a taking.
A
The Court’s conclusion that the restriction on particular coal does not work a taking is primarily the result of its view that the 27 million tons of coal in the ground “do not constitute a separate segment of property for takings law purposes.” Ante, at 498. This conclusion cannot be based on the view that the interests are too insignificant to warrant protection by the Fifth Amendment, for it is beyond cavil that government appropriation of “relatively small amounts of private property for its own use” requires just compensation. Ante, at 499, n„ 27. Instead, the Court’s refusal to recognize the coal in the ground as a separate segment of property for takings purposes is based on the fact that the *516alleged taking is “regulatory,” rather than a physical intrusion. See ante, at 488-489, n. 18. On the facts of this case, I cannot see how the label placed on the government’s action is relevant to consideration of its impact on property rights.
Our decisions establish that governmental action short of physical invasion may constitute a taking because such regulatory action might result in “as complete [a loss] as if the [government] had entered upon the surface of the land and taken exclusive possession of it.” United States v. Causby, 328 U. S. 256, 261 (1946). Though the government’s direct benefit may vary depending upon the nature of its action, the question is evaluated from the perspective of the property holder’s loss rather than the government’s gain. See ibid.; United States v. General Motors Corp., 323 U. S. 373, 378 (1945); Boston Chamber of Commerce v. Boston, 217 U. S. 189, 195 (1910). Our observation that “[a] ‘taking’ may more readily be found when the interference with property can be characterized as a physical invasion by government,” Penn Central Transportation Co. v. New York City, supra, at 124, was not intended to alter this perspective merely because the claimed taking is by regulation. Instead, we have recognized that regulations — unlike physical invasions — do not typically extinguish the “full bundle” of rights in a particular piece of property. In Andrus v. Allard, 444 U. S. 51, 66 (1979), for example, we found it crucial that a prohibition on the sale of avian artifacts destroyed only “one ‘strand’ of the bundle” of property rights, “because the aggregate must be viewed in its entirety.” This characteristic of regulations frequently makes unclear the breadth of their impact on identifiable segments of property, and has required that we evaluate the effects in light of the “several factors” enumerated in Penn Central Transportation Co.: “The economic impact of the regulation on the claimant, . . . the extent to which the regulation has interfered with investment-backed expectations, [and] the character of the governmental action.” 438 U. S., at 124.
*517No one, however, would find any need to employ these analytical tools where the government has physically taken an identifiable segment of property. Physical appropriation by the government leaves no doubt that it has in fact deprived the owner of all uses of the land. Similarly, there is no need for further analysis where the government by regulation extinguishes the whole bundle of rights in an identifiable segment of property, for the effect of this action on the holder of the property is indistinguishable from the effect of a physical taking.5 Thus, it is clear our decision in Andrus v. Allard, supra, would have been different if the Government had confiscated the avian artifacts. In my view, a different result would also follow if the Government simply prohibited every use of that property, for the owner would still have been “deprive[d] of all or most of his interest in the subject matter.” United States v. General Motors Corp. supra, at 378.
In this case, enforcement of the Subsidence Act and its regulations will require petitioners to leave approximately 27 million tons of coal in place. There is no question that this coal is an identifiable and separable property interest. Unlike many property interests, the “bundle” of rights in this coal is sparse. “Tor practical purposes, the right to coal consists in the right to mine it.’” Pennsylvania Coal, 260 *518U. S., at 414, quoting Commonwealth ex rel. Keater v. Clearview Coal Co., 256 Pa. at 331, 100 A. at 820. From the relevant perspective — that of the property owners — this interest has been destroyed every bit as much as if the government had proceeded to mine the coal for its own use. The regulation, then, does not merely inhibit one strand in the bundle, cf. Andrus v. Allard, supra, but instead destroys completely any interest in a segment of property. In these circumstances, I think it unnecessary to consider whether petitioners may operate individual mines or their overall mining operations profitably, for they have been denied all use of 27 million tons of coal. I would hold that § 4 of the Subsidence Act works a taking of these property interests.
B
Petitioners also claim that the Subsidence Act effects a taking of their support estate. Under Pennsylvania law, the support estate, the surface estate, and the mineral estate are “three distinct estates in land which can be held in fee simple separate and distinct from each other . . . Captline v. County of Allegheny, 74 Pa. Commw. 85, 91, 459 A. 2d 1298, 1301(1983), cert. denied, 466 U. S. 904 (1984). In refusing to consider the effect of the Subsidence Act on this property interest alone, the Court dismisses this feature of Pennsylvania property law as simply a “legalistic distinctio[n] within a bundle of property rights.” Ante, at 500. “Its value,” the Court informs us, “is merely a part of the entire bundle of rights possessed by the owner of either the coal or the surface.” Ante, at 501. See also 771 F. 2d 707, 716 (1985) (“To focus upon the support estate separately . . . would serve little purpose”). This view of the support estate allows the Court to conclude that its destruction is merely the destruction of one “strand” in petitioners’ bundle of property rights, not significant enough in the overall bundle to work a taking.
Contrary to the Court’s approach today, we have evaluated takings claims by reference to the units of property defined *519by state law. In Ruckleshaus v. Monsanto Co., for example, we determined that certain “health, safety, and environmental data” was “cognizable as a trade-secret property right under Missouri law,” 467 U. S., at 1003, and proceeded to evaluate the effects of governmental action on this state-defined property right.6 Reliance on state law is necessitated by the fact that “‘[pjroperty interests . . . are not created by the Constitution. Rather, they are created and their dimensions are defined by existing rules or understandings that stem from an independent source such as state law.’” Webb’s Fabulous Pharmacies, Inc. v. Beckwith, 449 U. S. 155, 161 (1980), quoting Board of Regents v. Roth, 408 U. S. 564, 577 (1972). In reality, the Court’s decision today cannot reject this necessary reliance on state law. Rather, it simply rejects the support estate as the relevant segment of property and evaluates the impact of the Subsidence Act by reference to some broader, yet undefined, segment of property presumably recognized by state law.
I see no reason for refusing to evaluate the impact of the Subsidence Act on the support estate alone, for Pennsylvania has clearly defined it as a separate estate in property. The Court suggests that the practical significance of this estate is limited, because its value “is merely part of the bundle of rights possessed by the owner of either the coal or the surface.” Ante, at 501. Though this may accurately describe the usual state of affairs, I do not understand the Court to mean that one holding the support estate alone would find it worthless, for surely the owners of the mineral or surface es-*520fates would be willing buyers of this interest.7 Nor does the Court suggest that the owner of both the mineral and support estates finds his separate interest in support to be without value. In these circumstances, where the estate defined by state law is both severable and of value in its own right, it is appropriate to consider the effect of regulation on that particular property interest.
When held by owners of the mineral estate, the support estate “consists of the right to remove the strata of coal and earth that undergird the surface . . . .” 771 F. 2d, at 715. Purchase of this right, therefore, shifts the risk of subsidence to the surface owner. Section 6 of the Subsidence Act, by making the coal mine operator strictly liable for any damage to surface structures caused by subsidence, purports to place this risk on the holder of the mineral estate regardless of whether the holder also owns the support estate. Operation of this provision extinguishes petitioners’ interests in their support estates, making worthless what they purchased as a separate right under Pennsylvania law. Like the restriction on mining particular coal, this complete interference with a property right extinguishes its value, and must be accompanied by just compensation.8
> I — I
In sum, I would hold that Pennsylvania s Bituminous Mine Subsidence and Land Conservation Act effects a taking of petitioners’ property without providing just compensation. Specifically, the Act works to extinguish petitioners’ interest *521in at least 27 million tons of coal by requiring that coal to be left in the ground, and destroys their purchased support estates by returning to them financial liability for subsidence. I respectfully dissent from the Court’s decision to the contrary.9
The Pennsylvania Supreme Court, in the decision under review, had also determined that the case called for “consideration ... of the constitutionality of the act itself.” Mahon v. Pennsylvania Coal Co., 274 Pa. 489, 494, 118 A. 491, 492 (1922). Before this Court, the coal company persisted in its claim that the Pennsylvania statute took its property without just compensation. See Brief for Plaintiff in Error in Pennsylvania Coal Co. v. Mahon, O. T. 1922, No. 549, pp. 7-8, 16, 19-21, 28-33; Brief for Defendants in Error in Pennsylvania Coal Co. v. Mahon, O. T. 1922, No. 549, p. 73.
That these were public “evils and abuses” is further illustrated by the coverage of the Kohler Act, which regulated mining under “any public building or any structure customarily used by the public,” including churches, schools, hospitals, theaters, hotels, and railroad stations. Mahon v. Pennsylvania Coal, supra, at 495, 118 A., at 492. Protected areas also included streets, roads, bridges, or “any other public passageway, dedicated to public use or habitually used by the public,” as well as public utility structures, private homes, workplaces, and cemeteries. Ibid.
The Court notes that the particulars of the Subsidence Act better serve these public purposes than did the Kohler Act. Ante, at 486. This may well be true, but our inquiry into legislative purpose is not intended as a license to judge the effectiveness of legislation. When considering the Fifth Amendment issues presented by Hawaii’s Land Reform Act, we noted that the Act, “like any other, may not be successful in achieving its intended goals. But ‘whether in fact the provisions will accomplish the objectives is not the question: the [constitutional requirement] is satisfied if. . . the . . . [State] Legislature rationally could have believed that the [Act] would promote its objective.’” Hawaii Housing Authority v. Midkiff, 467 U. S. 229, 242 (1984), quoting Western & Southern Life Insurance Co. v. State Bd. of Equalization, 451 U. S. 648, 671-672 (1981). Conversely, our cases have never found it sufficient that legislation efficiently achieves its desired objectives to hold that the compensation required by the Fifth Amendment is unavailable.
Plymouth Coal Co. v. Pennsylvania, 232 U. S. 531 (1914), did not go this far. Though the Court in that case upheld a statute requiring mine operators to leave certain amounts of coal in their mines, examination of the opinion in Plymouth Coal reveals that the statute was not challenged as a taking for which compensation was due. Instead, the coal company complained that the statutory provisions for defining the width of required pillars of coal were constitutionally deficient as a matter of procedural due process.
There is admittedly some language in Penn Central Transportation Co. v. New York City, 438 U. S. 104, 130-131 (1978), that suggests a contrary analysis: “ ‘Taking’ jurisprudence does not divide a single parcel into discrete segments and attempt to determine whether rights in a particular segment have been entirely abrogated. In deciding whether a particular governmental action has effected a taking, this Court focuses rather both on the character of the action and on the nature and extent of the interference with rights in the parcel as a whole.” The Court gave no guidance on how one is to distinguish a “discrete segment” from a “single parcel.” It was not clear, moreover, that the air rights at issue in Penn Central were entirely eliminated by the operation of New York City’s Landmark Preservation Law, for, as the Court noted, “it simply cannot be maintained, on this record, that appellants have been prohibited from occupying any portion of the airspace above the Terminal.” Id., at 136.
Indeed, we rejected the claim that the Supremacy Clause allowed Congress to dictate that the effect of its regulation “not vary depending on the property law of the State in which the submitter [of trade-secret information] is located. ... If Congress can ‘pre-empt’ state property law in the manner advocated . . . , then the Taking Clause has lost all vitality.” Ruckleshaus v. Monsanto Co., 467 U. S., at 1012.
It is clear that under Pennsylvania law, “one person may own the coal, another the surface, and the third the right of support.” Smith v. Glen Alden Coal Co., 347 Pa. 290, 304, 32 A. 2d 227, 234-235 (1943).
It is therefore irrelevant that petitioners have not presented evidence of “what percentage of the purchased support estates, either in the aggregate or with respect to any individual estate, has been affected by the Act.” Ante, at 501. There is no doubt that the Act extinguishes support estates. Because it fails to provide compensation for this taking, the Act violates the dictates of the Fifth Amendment.
Because I would find § 6 of the Subsidence Act unconstitutional under the Fifth Amendment, I would not reach the Contracts Clause issue addressed by the Court, ante, at 502-506.