Rule 401 – Test for Relevant Evidence

Evidence is relevant if:

(a) it has any tendency to make a fact more or less probable than it would be without the evidence; and

(b) the fact is of consequence in determining the action.

Summary and Explanation

Federal Rule of Evidence 401 defines what constitutes relevant evidence in a legal proceeding. This rule is a foundational aspect of the United States Federal Rules of Evidence, which govern the use of evidence in federal courts.

Key aspects of Rule 401 include:

  1. Definition of Relevant Evidence: According to Rule 401, evidence is considered relevant if:
    • It has any tendency to make a fact more or less probable than it would be without the evidence; and
    • The fact is of consequence in determining the action.
  2. Tendency to Prove or Disprove a Fact: This part of the rule emphasizes that for evidence to be relevant, it doesn’t need to conclusively prove a fact; it only needs to make the fact more or less likely to be true.
  3. Materiality: The fact that the evidence seeks to prove or disprove must be significant to the case—it must be a “fact of consequence.” This means the evidence must relate directly to the issues or elements in dispute in the case.
  4. Threshold for Relevance: The threshold for relevance under this rule is quite low. Evidence doesn’t need to be conclusive or even strongly indicative of a particular fact; it merely needs to contribute in some way to making a fact at issue more or less likely.
  5. Foundation for Admissibility: Rule 401 sets the basic standard for whether evidence should be admitted in court. Evidence that does not meet this relevance standard is generally inadmissible, although relevant evidence can still be excluded under other rules if its probative value is substantially outweighed by certain other factors.

Federal Rule of Evidence 401 establishes the criteria for determining the relevance of evidence in federal court. Evidence is relevant if it has any tendency to make a fact of consequence in the case more or less probable. This rule is crucial as it serves as the foundation for deciding whether evidence can be presented to the court.


(Pub. L. 93–595, §1, Jan. 2, 1975, 88 Stat. 1931; Apr. 26, 2011, eff. Dec. 1, 2011.)

Notes of Advisory Committee on Proposed Rules

Problems of relevancy call for an answer to the question whether an item of evidence, when tested by the processes of legal reasoning, possesses sufficient probative value to justify receiving it in evidence. Thus, assessment of the probative value of evidence that a person purchased a revolver shortly prior to a fatal shooting with which he is charged is a matter of analysis and reasoning.

The variety of relevancy problems is coextensive with the ingenuity of counsel in using circumstantial evidence as a means of proof. An enormous number of cases fall in no set pattern, and this rule is designed as a guide for handling them. On the other hand, some situations recur with sufficient frequency to create patterns susceptible of treatment by specific rules. Rule 404 and those following it are of that variety; they also serve as illustrations of the application of the present rule as limited by the exclusionary principles of Rule 403.

Passing mention should be made of so-called “conditional” relevancy. Morgan, Basic Problems of Evidence 45–46 (1962). In this situation, probative value depends not only upon satisfying the basic requirement of relevancy as described above but also upon the existence of some matter of fact. For example, if evidence of a spoken statement is relied upon to prove notice, probative value is lacking unless the person sought to be charged heard the statement. The problem is one of fact, and the only rules needed are for the purpose of determining the respective functions of judge and jury. See Rules 104(b) and 901. The discussion which follows in the present note is concerned with relevancy generally, not with any particular problem of conditional relevancy.

Relevancy is not an inherent characteristic of any item of evidence but exists only as a relation between an item of evidence and a matter properly provable in the case. Does the item of evidence tend to prove the matter sought to be proved? Whether the relationship exists depends upon principles evolved by experience or science, applied logically to the situation at hand. James, Relevancy, Probability and the Law, 29 Calif.L.Rev. 689, 696, n. 15 (1941), in Selected Writings on Evidence and Trial 610, 615, n. 15 (Fryer ed. 1957). The rule summarizes this relationship as a “tendency to make the existence” of the fact to be proved “more probable or less probable.” Compare Uniform Rule 1(2) which states the crux of relevancy as “a tendency in reason,” thus perhaps emphasizing unduly the logical process and ignoring the need to draw upon experience or science to validate the general principle upon which relevancy in a particular situation depends.

The standard of probability under the rule is “more * * * probable than it would be without the evidence.” Any more stringent requirement is unworkable and unrealistic. As McCormick §152, p. 317, says, “A brick is not a wall,” or, as Falknor, Extrinsic Policies Affecting Admissibility, 10 Rutgers L.Rev. 574, 576 (1956), quotes Professor McBaine, “* * * [I]t is not to be supposed that every witness can make a home run.” Dealing with probability in the language of the rule has the added virtue of avoiding confusion between questions of admissibility and questions of the sufficiency of the evidence.

The rule uses the phrase “fact that is of consequence to the determination of the action” to describe the kind of fact to which proof may properly be directed. The language is that of California Evidence Code §210; it has the advantage of avoiding the loosely used and ambiguous word “material.” Tentative Recommendation and a Study Relating to the Uniform Rules of Evidence (Art. I. General Provisions), Cal. Law Revision Comm’n, Rep., Rec. & Studies, 10–11 (1964). The fact to be proved may be ultimate, intermediate, or evidentiary; it matters not, so long as it is of consequence in the determination of the action. Cf. Uniform Rule 1(2) which requires that the evidence relate to a “material” fact.

The fact to which the evidence is directed need not be in dispute. While situations will arise which call for the exclusion of evidence offered to prove a point conceded by the opponent, the ruling should be made on the basis of such considerations as waste of time and undue prejudice (see Rule 403), rather than under any general requirement that evidence is admissible only if directed to matters in dispute. Evidence which is essentially background in nature can scarcely be said to involve disputed matter, yet it is universally offered and admitted as an aid to understanding. Charts, photographs, views of real estate, murder weapons, and many other items of evidence fall in this category. A rule limiting admissibility to evidence directed to a controversial point would invite the exclusion of this helpful evidence, or at least the raising of endless questions over its admission. Cf. California Evidence Code §210, defining relevant evidence in terms of tendency to prove a disputed fact.

Committee Notes on Rules—2011 Amendment

The language of Rule 401 has been amended as part of the restyling of the Evidence Rules to make them more easily understood and to make style and terminology consistent throughout the rules. These changes are intended to be stylistic only. There is no intent to change any result in any ruling on evidence admissibility.

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