Fed. R. Evid. 501

Privilege in General

The common law—as interpreted by United States courts in the light of reason and experience—governs a claim of privilege unless any of the following provides otherwise: • the United States Constitution; • a federal statute; or • rules prescribed by the Supreme Court. But in a civil case, state law governs privilege regarding a claim or defense for which state law supplies the rule of decision.

( Pub. L. 93–595, § 1 , Jan. 2, 1975 , 88 Stat. 1933 ; Apr. 26, 2011 , eff. Dec. 1, 2011 .)