Pennsylvania's support estate featured in at least two U.S. Supreme Court cases: Pennsylvania Coal Co. v. Mahon, 260 U.S. 393, 43 S. Ct. 158, 67 L.Ed. 322 (1922) and Keystone Bituminous Coal Association v. DeBenedictis 480 U.S. 470 (1987). Both ruled on attempts by the Pennsylvania legislature to transfer the support rights that the coal companies had bought and paid for to the owners of the surface rights, without compensation. The earlier case found that doing so violated the takings clause of the Fifth Amendment to the U.S. Constitution ("nor shall private property be taken for public use, without just compensation.") The later case found that it did not.
(The quotes below are from the opinion in the second case; I have reordered them somewhat in order to separate the discussion of the two cases)
"In Pennsylvania Coal Co. v. Mahon, 260 U.S. 393, 43 S. Ct. 158, 67 L.Ed. 322 (1922), the Court reviewed the constitutionality of a Pennsylvania statute that admittedly destroyed "previously existing rights of property and contract." Writing for the Court, Justice Holmes explained: "Government hardly could go on if to some extent values incident to property could not be diminished without paying for every such change in the general law. As long recognized, some values are enjoyed under an implied limitation and must yield to the police power. But obviously the implied limitation must have its limits, or the contract and due process clauses are gone. One fact for consideration in determining such limits is the extent of the diminution. When it reaches a certain magnitude, in most if not in all cases there must be an exercise of eminent domain and compensation to sustain the act. So the question depends upon the particular facts." Ibid. In that case the "particular facts" led the Court to hold that the Pennsylvania Legislature had gone beyond its constitutional powers when it enacted a statute prohibiting the mining of anthracite coal in a manner that would cause the subsidence of land on which certain structures were located.
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In Pennsylvania Coal, the Pennsylvania Coal Company had served notice on Mr. and Mrs. Mahon that the company's mining operations beneath their premises would soon reach a point that would cause subsidence to the surface. The Mahons filed a bill in equity seeking to enjoin the coal company from removing any coal that would cause "the caving in, collapse or subsidence" of their dwelling. The bill acknowledged that the Mahons owned only "the surface or right of soil" in the lot, and that the coal company had reserved the right to remove the coal without any liability to the owner of the surface estate. Nonetheless, the Mahons asserted that Pennsylvania's then recently enacted Kohler Act of 1921, P.L. 1198, Pa.Stat.Ann., Tit. 52, ' 661 et seq. (Purdon 1966), which prohibited mining that caused subsidence under certain structures, entitled them to an injunction.
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...In its argument in this Court, the company contended that the Kohler Act was not a bona fide exercise of the police power, but in reality was nothing more than " 'robbery under the forms of law' " because its purpose was "not to protect the lives or safety of the public generally but merely to augment the property rights of a favored few."
Over Justice Brandeis' dissent, this Court accepted the company's argument. In his opinion for the Court, Justice Holmes * * * rested on two propositions, both critical to the Court's decision. First, because it served only private interests, not health or safety, the Kohler Act could not be "sustained as an exercise of the police power." Second, the statute made it "commercially impracticable" to mine "certain coal" in the areas affected by the Kohler Act."
Stephens, J., in Keystone Bituminous Coal Association v. DeBenedictis 480 U.S. 470 (1987), summing up the decision of a previous Supreme Court in a similar case--while arguing that the facts were entirely different and the current majority could thus reach the opposite result without violating precedent.Justice Stephens summed up the case he was actually deciding:
"Pennsylvania's Subsidence Act authorizes the Pennsylvania Department of Environmental Resources (DER) to implement and enforce a comprehensive program to prevent or minimize subsidence and to regulate its consequences. Section 4 of the Subsidence Act, Pa.Stat.Ann., Tit. 52, ' 1406.4 (Purdon Supp.1986), prohibits mining that causes subsidence damage to three categories of structures that were in place on April 17, 1966: public buildings and noncommercial buildings generally used by the public; dwellings used for human habitation; and cemeteries. Since 1966 the DER has applied a formula that generally requires 50% of the coal beneath structures protected by ' 4 to be kept in place as a means of providing surface support. * * *
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In 1982, petitioners filed a civil rights action in the United States District Court for the Western District of Pennsylvania seeking to enjoin officials of the DER from enforcing the Subsidence Act and its implementing regulations. Petitioners are an association of coal mine operators, and four corporations that are engaged, either directly or through affiliates, in underground mining of bituminous coal in western Pennsylvania. * * * The complaint alleges that Pennsylvania recognizes three separate estates in land: The mineral estate; the surface estate; and the "support estate." Beginning well over 100 years ago, landowners began severing title to underground coal and the right of surface support while retaining or conveying away ownership of the surface estate. It is stipulated that approximately 90% of the coal that is or will be mined by petitioners in western Pennsylvania was severed from the surface in the period between 1890 and 1920. When acquiring or retaining the mineral estate, petitioners or their predecessors typically acquired or retained certain additional rights that would enable them to extract and remove the coal. Thus, they acquired the right to deposit wastes, to provide for drainage and ventilation, and to erect facilities such as tipples, roads, or railroads, on the surface. Additionally, they typically acquired a waiver of any claims for damages that might result from the removal of the coal. In the portions of the complaint that are relevant to us, petitioners alleged that both ' 4 of the Subsidence Act, as implemented by the 50% rule, and ' 6 of the Subsidence Act, constitute a taking of their private property without compensation in violation of the Fifth and Fourteenth Amendments.
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The holdings and assumptions of the Court in Pennsylvania Coal provide obvious and necessary reasons for distinguishing Pennsylvania Coal from the case before us today. The two factors that the Court considered relevant, have become integral parts of our takings analysis. We have held that land use regulation can effect a taking if it "does not substantially advance legitimate state interests, ... or denies an owner economically viable use of his land." Agins v. Tiburon, 447 U.S. 255 , 260, 100 S.Ct. 2138 , 2141, 65 L.Ed.2d 106 (1980) (citations omitted); see also Penn Central Transportation Co. v. New York City, 438 U.S. 104 , 98 S.Ct. 2646 , 2659, 57 L.Ed.2d 631 (1978). Application of these tests to petitioners' challenge demonstrates that they have not satisfied their burden of showing that the Subsidence Act constitutes a taking. First, unlike the Kohler Act, the character of the governmental action involved here leans heavily against finding a taking; the Commonwealth of Pennsylvania has acted to arrest what it perceives to be a significant threat to the common welfare. Second, there is no record in this case to support a finding, similar to the one the Court made in Pennsylvania Coal, that the Subsidence Act makes it impossible for petitioners to profitably engage in their business, or that there has been undue interference with their investment-backed expectations."
Arguably, the result in the first case depended on the fact that Pennsylvania, unlike most other states, recognized the support estate as a separate estate in land. If it had recognized only a mineral estate and a surface estate, the court might have found that the statute reduced but did not eliminate the mineral estate's value, hence was not a complete taking.
For a discussion of the underlying legal question--when taking part of a bundle of rights counts as sufficiently complete to implicate the takings clause of the Constitution--see Inverse Condemnation: The Search For The Relevant Parcel By Kevin J. Coakley.
For a discussion of Pennsylvania's recognition of three separate estates in land (surface, mineral, and support), Captline v. County of Allegheny, 662 A.2d 691 (Pa. Cmwlth. 1995).
For a much more extensive discussion of the issue of when a government action that reduces the value of someone's property is or ought to be considered a taking, and thus require compensation under the takings clause of the Constitution, see Richard Epstein's work, especially his book Takings.