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Key Facts
- Federal level: Rule 404(b) bars other-act evidence when it is offered to prove character and action in conformity with that character.
- Federal level: Other-act evidence may be admissible for a non-propensity purpose such as motive, intent, knowledge, identity, or absence of mistake.
- Federal level: The listed permitted purposes are examples, but the proposed purpose must genuinely matter to an issue other than character.
- Federal level: In a criminal case, the prosecutor must provide reasonable notice, identify the permitted purpose and supporting reasoning, and ordinarily do so in writing before trial.
- Federal level: Rule 403 remains an independent safeguard even when evidence is offered for a permitted Rule 404(b) purpose.
- Federal level: Under Huddleston, the judge does not first decide by a preponderance that the other act occurred; sufficient evidence must support a jury finding that it occurred.
What Federal Rule of Evidence 404(b) does
Federal Rule of Evidence 404(b) addresses evidence of a crime, wrong, or act other than the conduct at issue in the case. It prevents a party from using that evidence to argue that a person has a certain character and therefore acted consistently with it on the occasion being litigated.
The rule does not create a blanket ban on evidence involving other acts. It allows a court to consider the evidence when it is offered for another purpose, with motive, opportunity, intent, preparation, plan, knowledge, identity, absence of mistake, and lack of accident listed as examples.
Rule 404(b) is part of the broader Federal Rules of Evidence. Rule 1101 generally applies those rules in federal civil and criminal proceedings, subject to its listed exceptions, while Rule 404(b)’s notice provision specifically governs prosecutors in criminal cases.
The difference between propensity and a permitted purpose
A propensity inference moves from character to conduct: the person did something before, so the person likely behaved the same way this time. Rule 404(b)(1) prohibits that use.
A permitted-purpose theory instead connects the other act to a disputed issue without relying on character. In the Huddleston case, evidence involving sales of other allegedly stolen goods was offered on the disputed question whether the defendant knew the charged goods were stolen.
Naming “knowledge” or another item from the rule is not the entire analysis. The Supreme Court described the threshold inquiry as whether the evidence is probative of a material issue other than character.
Other-act evidence still faces additional gates
A proper non-propensity purpose does not make evidence automatically admissible. The evidence must be relevant, and Rule 403 permits exclusion when probative value is substantially outweighed by unfair prejudice, confusion, misleading the jury, delay, wasted time, or needless cumulative proof.
This distinction matters because damaging evidence is not necessarily unfairly prejudicial. The Rule 403 committee note describes unfair prejudice as an undue tendency to prompt a decision on an improper basis.
If evidence is admitted for one purpose but not another, Rule 105 provides another safeguard. On a timely request, the court must restrict the evidence to its proper scope and instruct the jury accordingly.
What Huddleston says about proof of the other act
Sometimes the relevance of Rule 404(b) evidence depends on whether the other act actually occurred. Rule 104(b) requires proof sufficient to support a finding that the conditional fact exists.
In Huddleston, the Supreme Court rejected a requirement that the district judge first find by a preponderance of the evidence that the other act occurred. The Court held that the evidence may go to the jury when sufficient evidence supports a finding by the jury that the person committed the other act.
This is a conditional-relevance standard, not permission to use the act for propensity. The offered evidence must still have a proper Rule 404(b) purpose and remain subject to the other evidence rules.
Criminal-case notice under Rule 404(b)(3)
The notice requirements apply when a prosecutor intends to offer Rule 404(b) evidence in a criminal case. The prosecutor must provide reasonable notice so the defendant has a fair opportunity to meet the evidence.
The notice must identify the permitted purpose and articulate the reasoning supporting that purpose. It must ordinarily be in writing before trial, although the court may excuse the lack of pretrial notice for good cause and allow notice in any form during trial.
The 2020 amendment strengthened these requirements and removed the former condition that the defendant first request notice. The rule does not impose one universal number of days; reasonableness depends on whether the timing gives the defendant a fair opportunity to meet the evidence.
A practical way to understand the court’s analysis
The analysis begins by identifying the other act and the precise non-propensity purpose for which it is offered. The court then considers whether the evidence is relevant to that purpose and, when occurrence of the act is disputed, whether Rule 104(b)’s sufficient-evidence standard is met.
The court also applies Rule 403 and considers whether a Rule 105 limiting instruction can confine the evidence to its proper use. In a criminal prosecution, compliance with Rule 404(b)(3)’s notice requirements is an additional question.
These are federal standards. State evidence codes and state-court interpretations may use different text, procedures, or tests and require separate state-specific research.
