Law originating from use and custom rather than from written statutes.
A question that pertains to the US constitution, acts of Congress, or treaties.Provides a basis for federal court jurisdiction.
PCP RULE: in diversity of citizenship cases, the federal court will apply the state law in 3 areas of evidence law:
C: competency of witnesses
three tests (1) a permanent physical occupation of the land is a taking (Loretto Taking); (2) a regulation so severe that there’s no economically viable use of the land after its application is a taking (Lucas Taking); (3) other regulatory takings are weighed under Penn Central test, which requires a three-part balancing test: (1) economic impact of the regulation, (2) land owner’s reasonable expectations when acquiring the land; (3) character of gov’t action.