Pennsylvania Coal Co. v. Mahon, 260 U.S. 393 (1922), was a case in which the Supreme Court of the United States held that whether a regulatory act constitutes a taking requiring compensation depends on the extent of diminution in the value of the property. The decision thereby started the doctrine of regulatory taking. The Takings Clause originally applied only when the government physically seized or occupied property. Prior to 1922, American courts followed a clear rule: regulation of land was not a taking. Rather, it was simply an exercise of the government’s police power to protect the public health, safety, welfare, and morals. Pennsylvania Coal also established the diminution-of-value test, in contrast to other tests, such as the permanent physical occupations test of Loretto v. Teleprompter Manhattan CATV Corp. (1982), the nuisance-control measures test of Hadacheck v. Sebastian (1915), and the total takings test of Lucas v. South Carolina Coastal Council (1992). Additionally, the case was one of the first to address the denominator problem with regard to regulatory taking. Parties Plaintiff/Respondent: H.J. Mahon, owner of surface rights to parcel of land. Defendant/Petitioner: Pennsylvania Coal Co., owner of mining rights to parcel of land. Background State of law In the late 19th century, the modern regulatory state was developing and the "scope of police regulation" was broadened. Whereas police regulations that restricted private property uses were originally thought to be used mostly to avoid noxious uses, police powers were expanding. Consequently, takings without compensation increased and the flaws of the previous takings doctrine, that exercises of police power could never be takings, became more apparent along with the need for changes in the takings law. At the time this case was decided, Mugler v. Kansas, "was the leading case standing for the proposition that an exercise of the police power could never be a taking ... even if they deprive property holders of all economic use of their property." Facts of case In an 1878 deed, the Pennsylvania Coal Co. granted to H.J. Mahon the surface rights to a parcel of land, but retained the mining rights to the land, and Mahon accepted any risk from, and waived all claim for damages resulting from, mining below the property. In 1921 the Commonwealth of Pennsylvania passed the Kohler Act, which prohibited the mining of anthracite coal in such way as to cause the subsidence of, among other things, any structure used