Evidence sample analysis
MBE Evidence Prior Bad Acts: MIMIC 404(b) Trap
Review a fresh FRE 404(b) prior-bad-acts hypo with examiner-style analysis on non-propensity admissibility, MIMIC purposes, and limiting instructions.
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Fact pattern
Daria is on trial for the armed robbery of the Westwood Credit Union on March 4. The robber wore a yellow ski mask, used a chrome revolver with a wooden grip, and forced the teller to hand over cash in a cloth bag stamped with a faded paw-print logo. The prosecution offers evidence that, two years earlier, Daria pleaded guilty to robbing a different credit union in another county. In that earlier robbery, the robber wore a yellow ski mask, used a chrome revolver with a wooden grip, and used a cloth bag stamped with the same faded paw-print logo. Daria objects under FRE 404(b), arguing the prior robbery is inadmissible character evidence. The prosecution responds that the prior act is offered to show identity, not propensity.
Quick answer
The court should admit the prior robbery for the limited purpose of proving identity, give a limiting instruction on request, and bar the jury from using the prior act as propensity evidence. Under FRE 404(b)(1), evidence of a prior 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. Under FRE 404(b)(2), the same evidence may be admissible for non-propensity purposes — commonly summarized by the MIMIC mnemonic: motive, intent, mistake (absence of), identity, and common plan or scheme. To use prior-act evidence for identity, the proponent must show a sufficiently distinctive modus operandi — a signature so unusual that it acts as a fingerprint linking the two acts. The proponent must also satisfy FRE 403 balancing and, on request, the court must give a limiting instruction under FRE 105.
IRAC analysis
May the prosecution introduce Daria's prior credit-union robbery to prove that she is the robber of the Westwood Credit Union, even though it would be excluded as propensity evidence?
Under FRE 404(b)(1), evidence of a prior 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. Under FRE 404(b)(2), the same evidence may be admissible for non-propensity purposes — commonly summarized by the MIMIC mnemonic: motive, intent, mistake (absence of), identity, and common plan or scheme. To use prior-act evidence for identity, the proponent must show a sufficiently distinctive modus operandi — a signature so unusual that it acts as a fingerprint linking the two acts. The proponent must also satisfy FRE 403 balancing and, on request, the court must give a limiting instruction under FRE 105.
The prosecution offers the prior robbery to prove identity, not to argue that Daria is a habitual robber. The two crimes share an unusually specific signature: the same yellow ski mask, the same chrome revolver with a wooden grip, and a cloth bag stamped with the same faded paw-print logo…
Primary law and source anchors
- Federal Rule of Evidence 404(b) Prior-act evidence inadmissible for propensity, admissible for non-propensity purposes (MIMIC).
- Federal Rule of Evidence 403 Balancing of probative value against unfair prejudice and other countervailing concerns.
- Federal Rule of Evidence 105 Court must give a limiting instruction on request when evidence is admissible for one purpose but not another.
- Huddleston v. United States, 485 U.S. 681 (1988) No preliminary finding of conditional fact is required; the jury must be able to find the prior act by a preponderance.