as a human habitation. Prior Pennsylvania law had recognized that such pillars of coal necessary to support the land surface were an estate in land (a “support estate”), separate from the rights in removable coal. Pennsylvania Coal provided notice to Mahon that it planned to mine for coal under the Mahon's habitation and Mahon brought suit to prevent Pennsylvania Coal from mining under his land pursuant to the Kohler Act. Prior history Mahon sued in the Court of Common Pleas to enjoin Pennsylvania Coal from conducting mining, but the court denied the injunction, holding the application of the Kohler Act to this case would be unconstitutional. The Supreme Court of Pennsylvania reversed, holding that the statute was a, "legitimate exercise of the police power" and granted an injunction. PA Coal v. Mahon, 43 Sup Ct. 412. Legal analysis Issues and Holdings Issue #1: Whether the Kohler Act as applied to the property in question constitutes an exercise of the police power, requiring no compensation, or of eminent domain, requiring compensation; -Holding #1: The Kohler Act as applied to the property in question constitutes an exercise of eminent domain, requiring compensation Issue #2: Whether the Kohler Act in general constitutes an exercise of the police power or of eminent domain. -Holding #2: The Kohler act in general constitutes an exercise of eminent domain. Rule of law The Court ruled that whether a regulatory act constitutes a taking requiring compensation depends on the extent of diminution in the value of the property. Reasoning The Court argued as follows: (1) The damage done by the activity prohibited by the act is a private, not a public nuisance; there is no public safety justification for the statute, as notice before mining would suffice to protect public safety. On the other hand, the damage done by the statute is significant, insofar as it abolishes an estate in land and a binding contract. (2) The statute, in general, purports to extinguish the mining rights to valuable properties under surfaces owned by the public and the government. The statute makes prohibitively expensive the mining of coal in these areas, and thereby effectively destroys the right, after all owning coal is not worth anything if the coal cannot be mined. The rights of the public to its streets and other property are rights paid for. If the representatives of the public have been so shortsighted as not to