In regulatory takings cases, the Court "compare the value that has been taken from the property with the value that remains in the property." The property that the Court analyzed was the whole parcel, not "discrete segments" of the whole property. So, the Court found that the 27 million tons of coal to be left in place was not "a separate segment of property for takings law purposes." Instead, the Court looked at the petitioners' total amount of coal. For this reason, the Court decided that the Subsidence Act had not denied the petitioners "economically viable use" of their coal mine properties and that their "reasonable 'investment-backed expectations'" in the properties had not been "materially affected."