Regulatory takings are government regulations of property that so restrict private use that the Takings Clause of the Fifth Amendment to the U.S. Constitution requires government compensation for the restrictions. This chapter presents two bright-line rules developed by federal courts to evaluate whether a land use regulation is a per se regulatory taking: government must compensate for obligating a property owner to suffer a trespass and government must compensate for taking all value in property. This chapter includes the following two cases: Loretto v. Teleprompter Manhattan CATV Corp. and Lucas v. South Carolina Coastal Council.