Federal Rules of Evidence – Rule 601 (through March 1, 2020)
Almost anyone can be a witness.
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.
Selected Committee Notes
This general ground-clearing eliminates all grounds of incompetency not specifically recognized in the succeeding rules of this Article. Included among the grounds thus abolished are religious belief, conviction of crime, and connection with the litigation as a party or interested person or spouse of a party or interested person. With the exception of the so-called Dead Man’s Acts, American jurisdictions generally have ceased to recognize these grounds.
The Dead Man’s Acts are surviving traces of the common law disqualification of parties and interested persons. They exist in variety too great to convey conviction of their wisdom and effectiveness. These rules contain no provision of this kind. For the reasoning underlying the decision not to give effect to state statutes in diversity cases, see the Advisory Committee’s Note to Rule 501.
No mental or moral qualifications for testifying as a witness are specified. Standards of mental capacity have proved elusive in actual application. A leading commentator observes that few witnesses are disqualified on that ground. Weihofen, Testimonial Competence and Credibility, 34 Geo. Wash.L.Rev. 53 (1965). Discretion is regularly exercised in favor of allowing the testimony. A witness wholly without capacity is difficult to imagine. The question is one particularly suited to the jury as one of weight and credibility, subject to judicial authority to review the sufficiency of the evidence. 2 Wigmore §§501, 509. Standards of moral qualification in practice consist essentially of evaluating a person’s truthfulness in terms of his own answers about it. Their principal utility is in affording an opportunity on voir dire examination to impress upon the witness his moral duty. This result may, however, be accomplished more directly, and without haggling in terms of legal standards, by the manner of administering the oath or affirmation under Rule 603.
Admissibility of religious belief as a ground of impeachment is treated in Rule 610. Conviction of crime as a ground of impeachment is the subject of Rule 609. Marital relationship is the basis for privilege under Rule 505. Interest in the outcome of litigation and mental capacity are, of course, highly relevant to credibility and require no special treatment to render them admissible along with other matters bearing upon the perception, memory, and narration of witnesses.