Character Evidence Rule (FRE 404) vs. Prior Bad Acts (FRE 404(b))
A detailed comparison of these two evidence rules, including key differences, exam strategies, and guidance on when to apply each.
Overview
FRE 404 and FRE 404(b) are part of the same rule but address different aspects of character evidence. FRE 404(a) establishes the general prohibition against using character evidence to prove that a person acted in conformity with a character trait on a particular occasion. This means the prosecution generally cannot introduce evidence that the defendant is a violent person to prove they committed a violent act. The rationale is that such propensity evidence is both unfairly prejudicial and of limited probative value.
FRE 404(b), however, carves out important exceptions by allowing evidence of prior bad acts for purposes other than proving character or propensity. The permitted purposes are often memorized using the mnemonic MIMIC: Motive, Intent, absence of Mistake, Identity, and Common plan or scheme (the rule also lists preparation, knowledge, and opportunity). When prior bad acts are offered for one of these non-propensity purposes, the evidence is admissible subject to the FRE 403 balancing test.
The interplay between these provisions is subtle. FRE 404(a) also contains exceptions for character evidence offered by the accused in a criminal case (the defendant can "open the door" by offering evidence of their own good character), after which the prosecution can rebut. In civil cases, character evidence is generally inadmissible for propensity purposes. FRE 404(b) applies in both civil and criminal cases and requires the prosecution in criminal cases to provide reasonable notice before trial of the specific acts it intends to introduce.
Key Differences
| Aspect | Character Evidence Rule (FRE 404) | Prior Bad Acts (FRE 404(b)) |
|---|---|---|
| General rule vs. exception | Establishes the general ban on character evidence to prove propensity | Provides exceptions allowing prior acts for non-propensity purposes |
| Purpose of evidence | Bars using character to show action in conformity on a specific occasion | Allows prior acts to show motive, intent, identity, plan, absence of mistake, etc. |
| Who opens the door | In criminal cases, only the defendant can introduce their own character first | Either party can offer prior acts evidence for a permitted purpose |
| Form of evidence | Character proved by reputation or opinion testimony (not specific acts on direct) | Specific instances of conduct are admissible |
| Notice requirement | No special notice requirement | Prosecution must give reasonable pretrial notice in criminal cases |
Exam Tips
Evidence exams love 404(b) questions. When you see prior bad acts evidence, your analysis should follow this structure: (1) Is the evidence being offered to prove propensity? If yes, it is barred by 404(a). (2) Is there a legitimate non-propensity purpose under 404(b)? Identify the specific purpose (MIMIC). (3) Does the evidence survive FRE 403 balancing? Even admissible 404(b) evidence can be excluded if its probative value is substantially outweighed by unfair prejudice. Always articulate the non-propensity purpose clearly and explain how the prior act logically serves that purpose without relying on a propensity inference.
When to Apply Which
Apply FRE 404(a) when the question is whether character evidence is admissible to prove that someone acted in conformity with a character trait. This is the threshold analysis. Apply FRE 404(b) when the evidence is a specific prior act and the proponent argues it is offered for a non-propensity purpose. Remember that even under 404(b), you must still run the 403 balancing test. In criminal cases, also consider whether the defendant has "opened the door" under 404(a)(2) by introducing their own good character evidence.