---
title: "Prior Bad Acts (FRE 404b)"
type: Legal Rule
source: https://casebriefly.com/legal-rules/prior-bad-acts-fre-404b
---

# Prior Bad Acts (FRE 404b)

Evidence of other crimes, wrongs, or acts is not admissible to prove character to show action in conformity, but may be admissible for other purposes such as motive, opportunity, intent, preparation, plan, knowledge, identity, absence of mistake, or lack of accident.

## Definition

Federal Rule of Evidence 404(b) addresses one of the most frequently litigated evidence issues: the admissibility of a person's prior bad acts. The rule begins with a clear prohibition — evidence of other crimes, wrongs, or acts cannot be used to prove that a person has a certain character and acted in conformity with it. This restates the propensity bar from FRE 404(a) in the specific context of extrinsic acts.

However, 404(b)(2) provides that such evidence may be admissible for other, non-propensity purposes. The rule lists several permitted uses: motive, opportunity, intent, preparation, plan, knowledge, identity, absence of mistake, or lack of accident. This list is illustrative, not exhaustive. Courts have recognized additional permissible purposes, including modus operandi (a distinctive pattern that serves as a signature) and consciousness of guilt. The key analytical question is always whether the evidence is being offered for a legitimate non-propensity purpose or whether it is merely a disguised attempt to show bad character.

To admit evidence under FRE 404(b), courts generally apply a multi-step analysis: the evidence must be offered for a proper non-propensity purpose, it must be relevant to that purpose, its probative value must not be substantially outweighed by unfair prejudice under FRE 403, and upon request the court must provide a limiting instruction. The prosecution must also provide reasonable pretrial notice of its intent to use such evidence. Prior bad acts need not have resulted in a conviction — even uncharged conduct qualifies if proved by sufficient evidence.

## Elements

- Evidence of other crimes, wrongs, or acts is being offered
- The evidence is NOT offered to prove character to show action in conformity (propensity is barred)
- The evidence IS offered for a permissible non-propensity purpose (e.g., MIMIC: Motive, Intent, Mistake absence, Identity, Common plan)
- The evidence is relevant to the permissible purpose under FRE 401
- The probative value is not substantially outweighed by unfair prejudice under FRE 403
- Reasonable pretrial notice must be given by the prosecution upon request

## Key Case

Huddleston v. United States, 485 U.S. 681 (1988)

## Landmark Cases

| Name | Citation | Significance |
| --- | --- | --- |
| Huddleston v. United States | 485 U.S. 681 (1988) | Held that prior bad acts need only be shown by sufficient evidence from which a jury could reasonably find the act occurred — no preliminary finding by the judge is required. |
| United States v. Beechum | 582 F.2d 898 (5th Cir. 1978) | Established the influential two-step test for 404(b) evidence: relevance to a material issue other than character, followed by FRE 403 balancing. |
| United States v. Dunnigan | 507 U.S. 87 (1993) | Addressed the boundary between prior acts evidence and character evidence, reinforcing that the proponent must articulate a specific non-propensity purpose. |
| United States v. Bray | 139 F.3d 531 (6th Cir. 1998) | Illustrative case demonstrating how courts apply the multi-factor test and FRE 403 balancing to prior acts evidence. |

## Exam Tips

- Use the MIMIC mnemonic (Motive, Intent, Mistake/absence, Identity, Common plan) to quickly recall the permissible purposes under 404(b).
- Always apply FRE 403 balancing after identifying a permissible purpose — the evidence can still be excluded if unfairly prejudicial.
- On exams, articulate exactly how the prior act is relevant to the non-propensity purpose without relying on a propensity inference in your chain of reasoning.
- Remember that 404(b) applies to both criminal and civil cases and to all parties, not just criminal defendants.

## Common Mistakes

- Treating the list of permissible purposes (motive, intent, etc.) as exhaustive — it is illustrative, and other non-propensity purposes are allowed.
- Failing to explain how the evidence connects to the non-propensity purpose without going through a propensity inference — the reasoning chain matters.
- Forgetting that even if a permissible purpose exists, the evidence must still survive FRE 403 balancing and the court should give a limiting instruction.

## Mnemonic Or Memory Aid

MIMIC: Motive, Intent, Mistake (absence of), Identity, Common plan/scheme.

## Related Rules

- character-evidence-rule-fre-404
- relevance-fre-401-403
- habit-evidence-fre-406
- impeachment-methods

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Source: [Prior Bad Acts (FRE 404b) — CaseBriefly](https://casebriefly.com/legal-rules/prior-bad-acts-fre-404b)