Pennsylvania Coal Co. v. Mahon

Case Overview

A coal company had kept the right to mine coal beneath land it sold, but Pennsylvania then passed a law forbidding mining that would cause the surface to cave in. The Supreme Court, through Justice Holmes, held that the law destroyed the company's mining right so completely that it amounted to a taking of property requiring compensation. Holmes's line that regulation which goes too far will be treated as a taking launched the entire doctrine of regulatory takings.