Fed. R. Evid. 601

Competency to Testify in General

Every person is competent to be a witness unless these rules provide otherwise. But in a civil case, state law governs the witness’s competency regarding a claim or defense for which state law supplies the rule of decision.

( Pub. L. 93–595, § 1 , Jan. 2, 1975 , 88 Stat. 1934 ; Apr. 26, 2011 , eff. Dec. 1, 2011 .)