Rule 501: Privilege in General

Rule 501 is unique among the Federal Rules of Evidence because it does not codify specific privileges. Instead, it directs federal courts to develop privilege law through the common law, interpreted in light of reason and experience. This means that federal privilege law evolves case by case rather than being frozen in a statutory code.

The rule creates an important distinction between federal-question and diversity cases. In federal-question cases (where jurisdiction is based on a federal statute or the Constitution), federal common law privilege applies. In diversity cases — civil cases where jurisdiction is based on the parties being from different states — state privilege law governs when state law supplies the rule of decision. This choice-of-law provision respects the principle that privileges reflect important state policies about confidential relationships.

Federal courts have recognized several well-established privileges under Rule 501, including attorney-client privilege, the psychotherapist-patient privilege (recognized in Jaffee v. Redmond), spousal privileges (both testimonial and communications), and the clergy-penitent privilege. The Supreme Court has declined to recognize other proposed privileges, such as a parent-child privilege or an accountant-client privilege.