3. Upon what sources may the federal court rely in developing a federal common law rule of decision? In many contexts, federal courts derive a federal common law rule from state common law sources, looking not simply at the common law rule of a particular state, but rather at the common law rules that operate in the majority of the states. See Nelson, The Persistence of General Law, 106 Colum. L. Rev. 503 (2006). The various facets of federal common law are discussed in 19 Wright, Miller & Cooper, Federal Practice and Procedure:

Jurisdiction and Related Matters 2d §§ 4514 4545.