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- Relevance is the starting point
- Relevant evidence can still be excluded
- The judge handles preliminary admissibility questions
- Authentication asks whether an item is what it claims to be
- Hearsay rules examine out-of-court statements
- Expert testimony has a separate reliability gate
- Common questions about admissible evidence
- Does relevant mean admissible?
- Can parties dispute weight or credibility after admission?
- Can a judge admit evidence conditionally?
- Sources
Key Facts
- Federal level: Evidence is relevant when it can make a consequential fact more or less probable than it would be without the evidence.
- Federal level: Relevant evidence is generally admissible unless the Constitution, a federal statute, or an applicable rule provides otherwise.
- Federal level: Rule 403 permits exclusion when specified dangers substantially outweigh probative value.
- Federal level: The judge decides preliminary questions about admissibility under Rule 104.
- Federal level: Rule 901 requires enough evidence to support a finding that an offered item is what its proponent claims.
Relevance is the starting point
Rule 401 defines relevant evidence through two linked requirements. The evidence must have some tendency to make a fact more or less probable, and that fact must matter in determining the action.
Rule 402 states that relevant evidence is admissible unless the United States Constitution, a federal statute, the Federal Rules of Evidence, or another Supreme Court rule provides otherwise. Irrelevant evidence is not admissible.
Relevant evidence can still be excluded
Rule 403 permits a court to exclude relevant evidence when its probative value is substantially outweighed by a danger of unfair prejudice, confusing the issues, misleading the jury, undue delay, wasting time, or needlessly presenting cumulative evidence.
The rule uses “unfair prejudice,” not simply damage to one side’s case. The balancing belongs to the court and depends on the proposed evidence, the reason it is offered, and the dangers identified in Rule 403.
The judge handles preliminary admissibility questions
Rule 104(a) directs the court to decide preliminary questions about whether a witness is qualified, a privilege exists, or evidence is admissible. In that inquiry, the court is not bound by evidence rules except those on privilege.
When relevance depends on whether a fact exists, Rule 104(b) requires proof sufficient to support a finding that the fact exists. The court may admit the evidence on the condition that the proof is introduced later.
Rule 104(e) preserves a party’s ability to present evidence relevant to the weight or credibility of other evidence.
Authentication asks whether an item is what it claims to be
Rule 901(a) requires evidence sufficient to support a finding that an offered item is what its proponent claims. Rule 901(b) lists examples rather than an exclusive set of methods.
Those examples include testimony from a witness with knowledge, distinctive characteristics considered with the circumstances, evidence describing an accurate process or system, and identification of a voice. The suitable method depends on the item and the claim made about it.
Hearsay rules examine out-of-court statements
Rule 801 defines hearsay as a statement the declarant does not make while testifying at the current trial or hearing when a party offers it to prove the truth of what it asserts.
Rule 802 generally bars hearsay unless a federal statute, the Federal Rules of Evidence, or another rule prescribed by the Supreme Court provides otherwise.
Expert testimony has a separate reliability gate
Rule 702 allows a qualified expert to testify when the proponent demonstrates that the specialized knowledge will help the factfinder, the testimony rests on sufficient facts or data, it results from reliable principles and methods, and the opinion reflects a reliable application to the case.
Expert credentials alone do not satisfy every part of Rule 702. The rule evaluates the proposed opinion, its basis, its methods, and their application.
Common questions about admissible evidence
Does relevant mean admissible?
Rule 402 recognizes constitutional, statutory, and rule-based grounds for excluding relevant evidence.
Can parties dispute weight or credibility after admission?
Rule 104(e) does not limit a party’s right to introduce evidence before the jury that is relevant to the weight or credibility of other evidence.
Can a judge admit evidence conditionally?
Rule 104(b) permits conditional admission when promised proof would allow a finding of the fact on which relevance depends.
