Mahon (P) received land from Pennsylvania Coal Co. (D) in 1878. In the deed, D reserved the mineral rights to the property, and it expressly stated that the grantee takes the premises with the risk, and waives all claims for damages that may arise from the mining out of the coal underneath the ground. P agreed not to object to their removal in the future, and not to ask for compensation for their removal. The state of Pennsylvania passed the Kohler Act in 1921. This Act disallowed the mining of coal in such a way as to cause the subsidence of any human habitation. After this Act was passed, D decided to claim its mineral rights, but P refused to allow D to do so. P asked for an injunction, claiming that D's actions would violate the Kohler Act, causing the subsidence of D's home. The trial court denied the injunction, claiming that the Act would be unconstitutional if applied to this case. The state Supreme Court reversed, granting the injunction and holding that the statute was a legitimate exercise of police power. D appealed, claiming that the Act violated due process, by allowing a taking without compensation.