Pennsylvania Coal Co. v. Mahon,
260 U.S. 393 (1922)

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U.S. Supreme Court

Pennsylvania Coal Co. v. Mahon, 260 U.S. 393 (1922)

Pennsylvania Coal Company v. Mahon

No. 549

Argued November 14, 1922

Decided December 11, 1922

260 U.S. 393


1. One consideration in deciding whether limitations on private property, to be implied in favor of the police power, are exceeded, is the degree in which the values incident to the property are diminished by the regulation in question, and this is to be determined from the facts of the particular case. P. 260 U. S. 413.

2. The general rule, at least, is that, if regulation goes too far, it will be recognized as a taking for which compensation must be paid. P. 260 U. S. 415.

3. The rights of the public in a street, purchased or laid out by eminent domain, are those that it has paid for. P. 260 U. S. 415.

4. Where the owner of land containing coal deposits had deeded the surface with express reservation of the right to remove all the coal beneath, the grantees assuming the risk and waiving all claim to damages that might arise from such mining, and the property rights thus reserved, and contracts made, were valid under the state law, and a statute, enacted later, forbade mining in such a way as to cause subsidence of any human habitation or public street or building, etc., and thereby made commercially impracticable the removal of very valuable coal deposits still standing unmined, held, that the prohibition exceeded the police power, whether viewed as a protection to private surface owners or to cities having only surface rights, and contravened the rights of the coal owner under the Contract Clause of the Constitution and the Due process Clause of the Fourteenth Amendment. * P. 260 U. S. 413.

274 Pa.St. 489 reversed.

Error to a decree of the Supreme Court of Pennsylvania, for the defendants in error, in their suit to enjoin the Coal Company from mining under their property in such a way as to remove supports and cause subsidence of the surface and of their house.

Page 260 U. S. 412

Primary Holding

A regulation that severely diminishes the value of private property amounts to a taking and requires compensation, although deference should be given to the legislature, and a case-by-case evaluation is required.


In a deed that transferred real estate from Pennsylvania Coal to Mahon, the company reserved the mineral rights on the property while Mahon waived the right to receive damages for the removal of minerals or to object to their removal. The company later chose to exercise its rights under the deed, but Mahon argued that this would violate the Kohler Act. This law had been enacted after the deed and prohibited mining activities that would cause the subsidence of a home.

Mahon sought an injunction against the company, which was granted by the lower court. The company appealed under the theory that the injunction was an unconstitutional taking of property under the Fifth Amendment.



  • Oliver Wendell Holmes, Jr. (Author)

Ruling that the Kohler Act was unconstitutional, Holmes argued that the public interest in protecting Mahon's surface rights did not warrant completely eradicating the property right to the minerals that the coal company had expressly reserved in the deed. He acknowledged that the state's police power may result in some interference with property rights, but the balance of interests weighed heavily in favor of the property owner in this situation.


  • Louis Dembitz Brandeis (Author)

Since the property technically had not changed owners or been taken by the state, Brandeis felt that the Fifth Amendment was not implicated here. He argued that the state had the right to prevent socially undesirable uses of property, such as mining on land where a home stands.

Case Commentary

This case used the diminution of value standard for determining whether a government action constituted a taking, and it was one of the first instances in which the Supreme Court addressed a situation in which virtually all value was removed from the property as a result. Although more recent cases have developed this line of doctrine further, the decision is still cited as an example of when a government goes too far in imposing restrictions on the land.

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