## **Learning Outcomes**

This article explains when evidence of other crimes, acts, transactions, or events is admissible under the Federal Rules of Evidence, including:

- Distinguishing impermissible propensity use from permissible non‑propensity purposes under Rule 404(b) and related character rules
- Applying the MIMIC framework (motive, intent, absence of mistake, identity, common plan) to dissect typical MBE‑style criminal and civil fact patterns
- Identifying and articulating the foundational requirements for admitting other‑acts evidence, including conditional relevance, sufficiency of proof, and notice obligations
- Evaluating Rule 403 unfair‑prejudice concerns, weighing probative value against the danger of misuse, and recognising when exclusion is strategically likely
- Formulating and critiquing limiting instructions that properly confine the jury’s use of other‑acts evidence to specific, non‑propensity purposes
- Comparing how courts treat other‑acts evidence in criminal versus civil cases, including the practical impact on burdens of proof and litigation strategy
- Differentiating other‑acts evidence from habit, impeachment, and same‑transaction evidence to avoid common exam traps and misclassifications
- Translating doctrinal principles into clear exam answers that identify the proponent’s purpose, analyse admissibility, and reach a supported conclusion on each step

## **MBE Syllabus**

For the MBE, you are required to understand the rules governing the admissibility of evidence of other crimes, acts, transactions, and events, with a focus on the following syllabus points:

- The general rule excluding evidence of other crimes or acts to prove character or propensity
- The recognised exceptions allowing such evidence for non‑propensity purposes (e.g., motive, intent, identity, absence of mistake, common plan)
- The requirements for admissibility and the need for sufficient proof of the other act
- The risk of unfair prejudice and the court’s discretion to exclude otherwise relevant evidence under Rule 403
- The distinction between criminal and civil cases regarding use of other‑acts evidence
- How Rule 404(b) interacts with other character rules (Rules 404(a), 405, 608, 609) and with habit evidence (Rule 406)

## **Test Your Knowledge**

_Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision._

1. Evidence that a defendant previously committed a similar crime is generally:
   a) Always admissible to show the defendant’s bad character.  
   b) Admissible only if the defendant testifies.  
   c) Inadmissible to prove propensity, but may be admissible for certain non-propensity purposes.  
   d) Admissible only in civil cases.

2. In a criminal trial, evidence that the defendant used the same unique method in a prior crime may be admitted to show:
   a) The defendant’s general criminal disposition.  
   b) Identity under the MIMIC exceptions.  
   c) The defendant’s right to remain silent.  
   d) The defendant’s motive to testify.

3. Which of the following is NOT a valid non-propensity purpose for admitting evidence of other acts?
   a) Motive.  
   b) Intent.  
   c) Propensity.  
   d) Absence of mistake.

## **Introduction**

Evidence of “other crimes, wrongs, or acts” is often powerful because it suggests, “this person has done it before.” That is exactly why the Federal Rules sharply restrict its use when offered to show that the person is the sort who commits that kind of act. At the same time, the same evidence can be extremely probative for other, legitimate purposes — for example, to show that a specific defence (“it was an accident”) is not credible.

On the MBE you must be able to:

- Spot when other‑acts evidence is being used for an impermissible propensity inference; and
- Recognise when it is properly used for a non‑propensity purpose, especially under the MIMIC rubric.

> **Key Term: Other-Acts Evidence**  
> Evidence that a party (usually the accused in a criminal case) committed crimes, wrongs, or other conduct separate from the charged event, regardless of whether those acts resulted in charges or convictions.

### The General Rule: Exclusion of Propensity Evidence

The starting point is the general bar in Rule 404(a) and (b): other‑acts evidence cannot be used to show character in order to prove action in conformity on a particular occasion.

> **Key Term: Propensity Evidence**  
> Evidence offered to show that a person has a particular character trait and acted in accordance with that trait on a specific occasion (e.g., “he’s a thief, so he probably stole this time”).

Rule 404(b)(1) states that evidence of a crime, wrong, or other act “is not admissible to prove a person’s character in order to show that on a particular occasion the person acted in accordance with the character.”

On the MBE, if the examiner’s explanation of relevance is simply, “he did it before, so he likely did it again,” you should immediately think: propensity — inadmissible.

> **Key Term: Rule 404(b)**  
> The rule governing use of “crimes, wrongs, or other acts.” It forbids using such evidence to show propensity, but allows it for specified non‑propensity purposes such as motive, intent, identity, and absence of mistake.

### Exceptions: Admissibility for Non‑Propensity Purposes (MIMIC and beyond)

Evidence of other acts may be admissible if offered for a purpose other than propensity. The most commonly tested non‑propensity purposes are captured by the acronym MIMIC:

- Motive
- Intent
- Absence of Mistake or accident
- Identity (including modus operandi)
- Common plan or scheme

> **Key Term: MIMIC Rule**  
> A shorthand for key non‑propensity uses of other‑acts evidence: motive, intent, absence of mistake, identity, and common plan or scheme.

Rule 404(b)(2) lists additional permissible non‑propensity purposes, including opportunity, preparation, and knowledge. On the exam, any of these can justify admitting other‑acts evidence if they are genuinely in issue.

Below are the core MIMIC categories, with exam‑style illustrations.

#### Motive

A prior act may show _why_ the person committed the charged act.

- Example: Prior assault against the same victim to show animus or revenge motive.
- Example: Prior insurance fraud scheme to show financial pressure motivating a staged accident.

The key is that the prior act explains the charged act; it is not just “more bad conduct.”

#### Intent

Where intent is an element (e.g., fraud, specific‑intent crimes), other similar acts can show that the defendant acted with the required state of mind.

- Prior scams using the same misrepresentation can show an intent to defraud, rather than an honest mistake.
- Prior drug sales can show that possessing large quantities of drugs now is not for personal use.

#### Absence of Mistake or Accident

Frequently tested when the defendant claims the conduct was accidental.

- Multiple similar “accidents” involving the same victim or circumstance suggest that the latest “accident” was intentional (sometimes called the “doctrine of chances”).

#### Identity (Modus Operandi)

Other‑acts evidence can prove identity if the method used is so unusual and distinctive that it serves as a “signature.”

- A burglar always leaves a purple playing card at the scene; that distinctive pattern can link prior burglaries to the charged one.

The more generic the similarity (“robbed convenience stores at night”), the less likely it will be admitted for identity.

#### Common Plan or Scheme

Other acts may show that the charged act is one step in a larger, unified plan.

- Example: A defendant who forges a deed, then forges a mortgage, then forges a sale contract; earlier forgeries can be used to show that the charged act is part of the overall scheme.

Note: This is not satisfied merely by “similar acts over time.” There must be some overall design tying the acts together.

### Requirements for Admissibility

Even when offered for a proper MIMIC (or other 404(b)(2)) purpose, other‑acts evidence does not automatically come in. Three key requirements must be satisfied:

- It is offered for a permissible, non‑propensity purpose.
- There is sufficient evidence that the other act occurred.
- Its probative value is not substantially outweighed by unfair prejudice under Rule 403.

#### 1. Proper Purpose and Material Issue

The purpose must be genuinely in dispute and material to the case. If the defendant concedes identity and only disputes whether a crime occurred at all, identity‑based other‑acts evidence is likely irrelevant and inadmissible.

On the exam, ask: _What issue does this evidence help decide, other than “he is the type who does this”?_ If you cannot articulate a non‑propensity issue (motive, intent, etc.), it is inadmissible.

#### 2. Sufficient Proof: Conditional Relevance and Standard of Proof

The judge must be satisfied that a reasonable jury could find that the other act occurred and that the defendant was the actor, typically by a preponderance of the evidence. This is a Rule 104(b) “conditional relevance” question.

> **Key Term: Rule 403 Balancing**  
> The process by which a court may exclude relevant evidence if its probative value is substantially outweighed by dangers such as unfair prejudice, confusion, or waste of time.
>
> **Key Term: Limiting Instruction**  
> A jury instruction directing jurors to consider evidence for a specified permissible purpose but not for an impermissible one (e.g., “may consider prior act only for intent, not to show bad character”).

The prosecution does not need to prove the prior act beyond a reasonable doubt; a prior conviction is not required. Police reports, testimony of the prior victim, or other admissible evidence can suffice.

#### 3. Rule 403: High Risk of Unfair Prejudice

Even with a proper purpose and sufficient proof, other‑acts evidence is often excluded under Rule 403 because it carries a high risk that the jury will misuse it for propensity. Factors relevant to the 403 analysis include:

- How similar the prior act is to the charged act
- How necessary the evidence is to prove the non‑propensity point (e.g., is there alternative, less prejudicial evidence?)
- The closeness in time
- Whether the court can effectively limit prejudice with a clear limiting instruction

If admitted, the court should, on request, give a limiting instruction under Rule 105, telling the jury it may consider the evidence only for the specified non‑propensity purpose.

> **Key Term: Rule 403 Balancing** (revisited)  
> In this context, the judge weighs the strong probative value of other‑acts evidence for a MIMIC purpose against the substantial risk that jurors will convict because they think the defendant is a bad person.

### Worked Example 1.1

A defendant is on trial for arson. The prosecution seeks to introduce evidence that the defendant set fire to another building five years earlier using the same rare accelerant and method. The defendant objects, arguing this is inadmissible character evidence.

> **Answer:**  
> The evidence is not being offered to show propensity, but to show identity through a unique modus operandi (MIMIC: Identity). If the prosecution can show sufficient proof that the prior act occurred and the method is distinctive, the evidence may be admitted, subject to Rule 403 balancing and a limiting instruction on identity.

### Worked Example 1.2

In a fraud case, the plaintiff offers evidence that the defendant previously used the same false documents in a different transaction with another victim. Is this evidence admissible?

> **Answer:**  
> Yes, if offered to show intent to defraud or absence of mistake, not to show the defendant’s general dishonesty. The court must still weigh the probative value against the risk of unfair prejudice under Rule 403 and, on request, instruct the jury to consider it only for intent or absence of mistake.

### Worked Example 1.3

A defendant is prosecuted for possession with intent to distribute cocaine. He claims he thought the package contained powdered milk. The prosecution wants to introduce evidence that the defendant has twice previously sold cocaine to undercover officers.

> **Answer:**  
> The prior sales are inadmissible to show that the defendant is a “drug dealer” by propensity, but they are admissible to show knowledge and absence of mistake about the nature of the substance in the current case, and to show intent to distribute. The judge must find sufficient proof of the prior sales and then perform Rule 403 balancing; a limiting instruction should restrict the jury’s use of the evidence to knowledge and intent.

### Same‑Transaction vs Extrinsic Acts

Not every bad act surrounding the charged conduct is a “404(b) other act.” Some conduct is so closely connected with the charged offence that it is treated as part of the charged offence — for example:

- Acts that are part of the same transaction or occurrence
- Background facts that complete the story of the crime

Such acts are not governed by Rule 404(b), but they still must pass Rule 403.

### Criminal vs Civil Cases

Rule 404(b) applies in both criminal and civil cases.

- **Criminal cases:** Other‑acts evidence is most often offered by the prosecution to prove a MIMIC purpose. Federal prosecutors must provide reasonable pretrial notice of their intent to use 404(b) evidence if the defendant requests it.
- **Civil cases:** Other‑acts evidence is admissible for non‑propensity purposes on the same terms, but character is rarely a material issue in civil litigation. Typical uses include proving intent or knowledge in fraud or misrepresentation actions, or proving notice of a dangerous condition in negligence.

Remember: separate rules (Rules 413–415) allow limited propensity evidence in federal sexual‑assault and child‑molestation cases. Those are narrow statutory exceptions; otherwise, propensity is barred.

### Relationship to Other Character Rules

On the MBE, you must distinguish other‑acts evidence under 404(b) from other, superficially similar doctrines:

- **Character evidence under Rule 404(a):**  
  When the accused offers a character witness (reputation or opinion) for a relevant trait, the prosecution may rebut with reputation or opinion — not specific bad acts.
- **Impeachment under Rules 608 and 609:**  
  Specific acts may be asked about on cross‑examination if they relate to truthfulness (Rule 608(b)), and certain convictions may be admitted (Rule 609). The purpose is to attack credibility, not to prove conduct on a specific occasion.
- **Habit evidence under Rule 406:**  
  Evidence of a person’s regular response to a specific situation may be used to show conduct in conformity with that habit. Habit is more automatic and specific than general character; other‑acts evidence under 404(b) is not habit.

### Exam Warning

> Evidence of other acts is never admissible solely to show that a person is the type to commit the charged act. Always identify the specific, non‑propensity purpose for which the evidence is offered. Courts will strictly enforce this rule.

### Exam Strategy Tip

> When analysing an MBE question, ask in this order:
>
> - What is the stated purpose for the other‑acts evidence?
> - Is that purpose a valid MIMIC (or similar 404(b)(2)) purpose that is genuinely in issue?
> - Has the proponent offered enough proof that the other act occurred?
> - Is the probative value substantially outweighed by unfair prejudice under Rule 403?
> - If admissible, would a limiting instruction be appropriate?

## **Key Point Checklist**

_This article has covered the following key knowledge points:_

- Other‑acts evidence (crimes, wrongs, or other acts) is generally inadmissible to show character or propensity under Rule 404(b)(1).
- Such evidence may be admitted for non‑propensity purposes under Rule 404(b)(2), commonly summarised as MIMIC: motive, intent, absence of mistake, identity, and common plan or scheme (plus opportunity, preparation, and knowledge).
- The issue to which the evidence is directed must be material and genuinely disputed; otherwise the evidence is irrelevant.
- The judge must find sufficient evidence that the other act occurred, generally by a preponderance of the evidence under Rule 104(b) conditional relevance.
- Even when offered for a proper purpose, other‑acts evidence is subject to Rule 403 balancing and may be excluded if its probative value is substantially outweighed by unfair prejudice.
- If admitted, the court should give a limiting instruction on request, restricting the evidence to the permissible non‑propensity purpose.
- Rule 404(b) applies in both criminal and civil cases, but other‑acts evidence is most frequently used in criminal prosecutions.
- Distinguish Rule 404(b) other‑acts evidence from character evidence under Rule 404(a), impeachment (Rules 608–609), and habit evidence (Rule 406).
- Acts that are part of the same transaction or necessary background are not treated as 404(b) “other acts” but still must satisfy Rule 403.
- Sexual‑assault and child‑molestation cases have separate statutory rules (Rules 413–415) that allow limited propensity use; these are exceptions to the general bar.

## **Key Terms and Concepts**

- Other-Acts Evidence
- Propensity Evidence
- Rule 404(b)
- MIMIC Rule
- Rule 403 Balancing
- Limiting Instruction

Relevancy and reasons for excluding relevant evidence - Other crimes, acts, transactions, and events