Rule 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; amended Apr. 26, 2011, eff. Dec. 1, 2011.)