Federal Rules of Evidence

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The Federal Rules of Evidence is a body of rules which governs evidence law in civil proceedings in United States federal courts. Rule 102 states that the purpose of the rules is to “administer every proceeding fairly, eliminate unjustifiable expense and delay, and promote the development of evidence law, to the end of ascertaining the truth and securing a just determination.” Rule 104 places the focus of the rules to three main preliminary inquiries: whether a witness is qualified, a privilege exists, or evidence is admissible. Additionally, among many other topics, the rules govern judicial notice, relevancy, testimony, proving character, and hearsay


Throughout history and even today, evidence law has been greatly influenced by and central to the Anglo-American practice of utilizing juries to fact-find. John Langbein, in a Yale Law Journal article, Historical Foundations of the Law of Evidence: A View from the Ryder Sources, depicts Anglo-American law of evidence as driven “to protect against the shortcomings of trial by jury,” as “[j]urors are untrained in the law, they decide without giving reasons, they have no continuing responsibility for the consequences of their decisions, and their verdicts are quite difficult to review.” Given evidence law’s intertwined history with the ancient practice of trial by jury, most Anglo-American courts followed the common law of evidence until the adoption of the Federal Rules of Evidence. 

Federally, the First Congress provided minimal guidance on evidentiary rules to be used in federal courts, relying instead on the common law of the states. The Judiciary Act of 1789 required the federal courts follow state procedure law for actions in courts of law as they existed in 1789, and this largely included evidentiary rules. Constitutional amendments, such as the Sixth Amendment, also provided a degree of guidance for evidentiary law in federal courts. However, evidence law in federal courts remained an amalgamation of the varied state common law procedures through the 18th and 19th century. The Conformity Act of 1872 reinforced this, by requiring that “nothing herein contained shall alter the rules of evidence under the laws of the United States”—i.e. the state laws of evidence as they existed in 1789 (or at the time of admission to the union). 

Through the beginning of the 20th century, federal courts still treated evidence law predominantly as a matter of common law. For example, Southwest Metals Co. v. Gomez, a 1925 Ninth Circuit case, cited legal encyclopedia and federal case law on whether hypothetical questions must be used in questioning experts after applying state law to privilege issues. 1938, however, provided impetus for federal uniformity in evidence law, as the U.S. Supreme Court promulgated the Federal Rules of Civil Procedure and England overhauled its evidence law in the Evidence Act of 1938. Furthermore, the Rules Enabling Act of 1934 gave the U.S. Supreme Court the power to promulgate rules of evidence for civil proceedings in federal court, if it chose to do so. 

After years of commentators pushing for uniform federal evidence reform, the U.S. Supreme Court appointed a Special Committee on Evidence, which agreed in 1963 to draft a uniform set of rules for evidence law in federal civil proceedings. The Supreme Court approved the new evidentiary rules in 1972, but awaited Congressional approval. Questions around government privilege and other evidentiary matters surrounding Watergate, however, in part delayed Congress’s approval of the uniform set of evidentiary rules, and Congress took an increased interest in the rules. Finally, in 1975, Congress, after considerable deliberation, approved the Federal Rules of Evidence in Pub. L. 93–595.

The biggest reform that the new rules instituted was a uniform set of evidentiary rules for all federal civil proceedings. However, in addition to providing uniformity, the new federal rules also altered or abrogated many common law doctrines. One major provision was Rule 401, which provides a standard for relevance. Another is Rule 403, which gives judges discretion to exclude otherwise relevant evidence to avoid undue prejudice, confusion, or time wasting. Rule 803 substantially abrogated the common law exclusion of res gestae witness testimony. Additionally, since its initial adoption, some amendments have been added to the rules. For example, Rule 412, adopted in 1978, provides evidentiary rules for proceedings on sex-offenses. Most recently, the Advisory Committee made many stylistic changes in 2011, for example by simplifying the language of Rule 401

[Last updated in May of 2021 by the Wex Definitions Team]