M.R.E. 404(b): Uncharged Misconduct
Key takeaways
- The propensity inference is prohibited: other acts cannot be used to show the accused is the kind of person who commits offenses. M.R.E. 404(b)(1).
- The same evidence is admissible for non-propensity purposes — motive, opportunity, intent, preparation, plan, knowledge, identity, absence of mistake — and the list is not exhaustive. United States v. Castillo, 29 M.J. 145 (C.M.A. 1989).
- Admissibility runs through the three-part test of United States v. Reynolds, 29 M.J. 105 (C.M.A. 1989): sufficient proof of the act, relevance to a fact of consequence, and M.R.E. 403 balancing.
- On request by the accused, the prosecution must give reasonable pretrial notice of the general nature of any 404(b) evidence it intends to offer. M.R.E. 404(b)(2).
- When 404(b) evidence is admitted, the members must be clearly instructed on its narrow, limited purpose — a defective instruction is reversible. United States v. Rhodes, 61 M.J. 445 (C.A.A.F. 2005).
The rule: propensity vs. everything else
M.R.E. 404(b) draws the line that decides more contested courts-martial than any other evidence rule. On one side sits the forbidden inference — that because the accused did something bad before, he probably did the charged offense too.
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.
M.R.E. 404(b)(1)
On the other side sits nearly everything else. M.R.E. 404(b) is an inclusive rule: extrinsic-act evidence is admissible unless its sole purpose is to show criminal disposition. The “sole test” is whether the evidence is offered for some purpose other than to demonstrate the accused’s predisposition to crime; relevant evidence need not “fit snugly into a pigeon hole” provided by the rule. United States v. Castillo, 29 M.J. 145, 150 (C.M.A. 1989). If the proponent can articulate a non-propensity theory of relevance, the military judge has discretion to admit after applying M.R.E. 403. The framework for that whole analysis sits inside the Military Rules of Evidence relevance structure — and it stands in deliberate contrast to M.R.E. 413 and 414, which allow true propensity evidence in sexual offense cases only.
The permitted purposes — KIPPOMIA
Military practitioners memorize the permitted purposes as KIPPOMIA: Knowledge, Intent, Plan, Preparation, Opportunity, Motive, Identity, Absence of mistake. Each carries its own doctrine:
- Motive supplies the reason that “nudges the will” toward criminal intent; the prior acts must reasonably express the same internal emotion existing at the time of the charged acts. United States v. Watkins, 21 M.J. 224 (C.M.A. 1986). A concealed relationship was admissible to show the motive behind a sham-marriage fraud. United States v. Phillips, 52 M.J. 268 (C.A.A.F. 2000).
- Intent negates accident or inadvertence. The accused’s state of mind in the uncharged act must be sufficiently similar to permit meaningful comparison with the charged offense. United States v. McDonald, 59 M.J. 426, 430 (C.A.A.F. 2004). The “doctrine of chances” also lives here: the sheer number of injuries to a child over a short period rebuts any inference of accident. United States v. Merriweather, 22 M.J. 657 (A.C.M.R. 1986). Stalking a former wife in a similar manner proved intent to inflict emotional distress on the current one. United States v. Sweeney, 48 M.J. 117 (C.A.A.F. 1998).
- Plan requires a prior mental resolve with worked-out particulars — and courts examine the relationship, ages, nature, location, circumstances, and time span of the acts. Dissimilar acts do not make a plan. Compare United States v. Munoz, 32 M.J. 359 (C.M.A. 1991), with McDonald, where 20-year-old acts committed at age 13 could not establish a common plan.
- Identity demands modus operandi so similar it is “a signature marking the offense as the handiwork of the accused.” United States v. Gamble, 27 M.J. 298, 305 (C.M.A. 1988).
- Consciousness of guilt — aggressive intimidation of the trial counsel qualified, with a carefully tailored instruction. United States v. Staton, 69 M.J. 228 (C.A.A.F. 2010). But a meeting followed by a witness’s sudden memory loss did not, without more. United States v. Rhodes, 61 M.J. 445 (C.A.A.F. 2005).
The Reynolds three-part test
Since 1989, every 404(b) offer has been measured against the three-part test of United States v. Reynolds, 29 M.J. 105, 109 (C.M.A. 1989):
| Prong | Question | Standard |
|---|---|---|
| 1. Proof of the act | Does the evidence reasonably support a finding that the accused committed the prior crime, wrong, or act? | Conditional relevance under M.R.E. 104(b) — could the members reasonably find it? No preponderance finding required. Huddleston v. United States, 485 U.S. 681 (1988) |
| 2. Relevance | Does the evidence make a fact of consequence more or less probable — without character as a necessary link in the chain? | If the intended inference runs through propensity, the evidence is excluded |
| 3. Balancing | Is the probative value substantially outweighed by the danger of unfair prejudice? | M.R.E. 403, with the Berry factors |
Each prong has killed government evidence. In United States v. Diaz, 59 M.J. 79 (C.A.A.F. 2003), a “pattern of abuse” theory failed all three: the government never showed the accused inflicted the other injuries, the evidence answered no defense actually raised, and the prejudice outweighed the proof. In McDonald, prong two failed — the CAAF called the relevance ruling “fanciful and clearly unreasonable.” In United States v. Thompson, 63 M.J. 228 (C.A.A.F. 2006), evidence of preservice drug use failed prong two because the accused had never raised lack of knowledge or mistake. And military courts apply the test strictly: the Air Force court has observed that M.R.E. 404(b) is interpreted more restrictively in military jurisprudence than in other federal courts. United States v. Harrow, 62 M.J. 649, 660 (A.F. Ct. Crim. App. 2006).
The notice requirement
On request by the accused, the prosecution must provide reasonable notice of the general nature of any 404(b) evidence it intends to offer at trial — and must do so before trial, unless the military judge excuses pretrial notice for good cause. M.R.E. 404(b)(2). The request should be a standing item in every defense discovery demand, because notice is what makes the Reynolds fight winnable: it forces the government to commit to a theory of admissibility in advance, gives the defense time to attack the proof of the underlying act, and frames the motion in limine. Undisclosed 404(b) evidence surfacing mid-trial is an objection, a continuance request, and occasionally a mistrial motion — part of the broader motions practice covered in our court-martial motions guide.
What this means if the government is digging through your past
When investigators start interviewing ex-spouses, old roommates, and prior units, they are building a 404(b) case — a way to convict you of this offense by proving you did other things at other times. Every one of those acts must pass the Reynolds test, and most fail when the defense forces the government to name a non-propensity purpose and prove the act actually happened. Do not discuss old allegations with anyone, and get defense counsel involved before the government’s theory hardens — the notice demand and the motion in limine only protect you if someone files them.
The 403 battleground
Commentators note that M.R.E. 403’s greatest value may be in resolving 404(b) issues, because the threshold of proof for the extrinsic act is so low. The judge weighs the strength of proof of the prior act, its probative weight, the availability of less prejudicial alternatives, the distraction and time the proof will consume, temporal proximity, frequency, intervening circumstances, and the relationship between the parties — the Berry factors, 61 M.J. 91 (C.A.A.F. 2005). Special findings on the record are expected, and a judge who conducts a proper balancing gets deferential review while one who merely recites the rule does not. United States v. Hursey, 55 M.J. 34 (C.A.A.F. 2001); United States v. Bins, 43 M.J. 79 (C.A.A.F. 1995).
Even offensive material can survive: in United States v. Hays, 62 M.J. 158 (C.A.A.F. 2005), explicit e-mails and images were admitted in a child-solicitation case because their prejudicial impact did not substantially outweigh their value on intent and motive. But the defense cannot force a sanitizing stipulation — absent an Old Chief situation, the government may prove its 404(b) evidence in the form it chooses. United States v. Crowder, 141 F.3d 1202 (D.C. Cir. 1998) (en banc).
Government uses and defense counters
The government’s standard plays — and the counters that work:
- “Pattern” theories. Counter with Diaz: pattern is often propensity wearing a lab coat. Demand the specific non-propensity purpose and the fact of consequence it serves.
- Intent evidence against a general-denial defense. Counter with Thompson: if the defense has not raised lack of knowledge or mistake, the evidence may answer nothing in issue. But beware United States v. Harrow, 65 M.J. 190 (C.A.A.F. 2007) — the government may prove intent and absence of accident regardless of the defense theory when the defense’s own evidence puts accident in play, because every element must be proven.
- Old or youthful acts. Counter with McDonald and United States v. Berry: acts committed years earlier, especially as an adolescent, rarely permit a meaningful comparison of mental states.
- Post-offense acts. Timing cuts both ways — later drug activity proved earlier knowledge in United States v. Latney, 108 F.3d 1446 (D.C. Cir. 1997), but a later positive urinalysis could not prove knowing use on the charged date. United States v. Matthews, 53 M.J. 465 (C.A.A.F. 2000).
- Prior acquittals. An acquittal does not bar the evidence — collateral estoppel does not preclude otherwise admissible acts. United States v. Mundell, 40 M.J. 704 (A.C.M.R. 1994); Dowling v. United States, 493 U.S. 342 (1990). The counter shifts to prongs two and three.
- Instructions. When evidence is admitted, insist on a clear, simple, correct limiting instruction on its narrow purpose; a defective one reversed Rhodes. At sentencing, remember the lane change: uncharged misconduct in presentencing is controlled by R.C.M. 1001’s aggravation rules, not 404(b).
One more lane to watch: uncharged sexual offenses offered in an Article 120 case may come in under 404(b) or under the propensity rules — but propensity is never a proper 404(b) purpose, and a judge who says “propensity” while ruling under 404(b) has erred. United States v. Yammine, 69 M.J. 70 (C.A.A.F. 2010). The distinct 413/414 framework — and its limits — is covered in the propensity evidence deep dive, and the rape shield counterpart in the M.R.E. 412 guide.
Practitioner’s note
In our practice, we treat every 404(b) notice as three separate motions waiting to be written. First we attack prong one with the underlying proof — the government often has an allegation, not evidence a panel could reasonably credit. Then we force prong two into the open by making the trial counsel articulate, on the record, the inference chain from act to fact of consequence; if the chain passes through “he’s the type,” it dies there. Finally we brief the Berry factors with specifics — dates, dissimilarities, intervening years — because judges who make special findings need material to make them with, and the side that supplies the findings usually wins the ruling.
Frequently asked questions
What is M.R.E. 404(b) in a court-martial?
It is the rule governing uncharged misconduct. Evidence of a crime, wrong, or other act cannot be used to prove the accused's character and show action in conformity with it, but the same evidence may be admitted for non-propensity purposes such as motive, opportunity, intent, preparation, plan, knowledge, identity, or absence of mistake. The listed purposes are illustrative, not exhaustive.
What is the Reynolds test?
The three-part test from United States v. Reynolds, 29 M.J. 105 (C.M.A. 1989), that military judges apply to uncharged misconduct: whether the evidence reasonably supports a finding that the accused committed the prior act, whether it makes a fact of consequence more or less probable without relying on character, and whether its probative value is substantially outweighed by the danger of unfair prejudice under M.R.E. 403.
Does the prosecution have to tell the defense about 404(b) evidence before trial?
Yes, if asked. On request by the accused, the prosecution must provide reasonable notice of the general nature of any 404(b) evidence it intends to offer, and must do so before trial unless the military judge excuses pretrial notice for good cause. Defense counsel should make the request in every case so the admissibility fight happens in motions, not mid-trial.
How strong does the proof of the prior act have to be?
Modest. Under the conditional-relevance standard of Huddleston and M.R.E. 104(b), the judge does not weigh credibility or require proof by a preponderance — only enough evidence that the members could reasonably find the accused committed the act. That low threshold is why the M.R.E. 403 balancing and the relevance prong carry so much of the defense fight.
Can I be convicted based on things I was already acquitted of?
A prior acquittal does not automatically keep the underlying acts out. Under Dowling v. United States and military cases applying it, collateral estoppel does not preclude otherwise admissible evidence of acts tried to acquittal. The defense counter runs through the Reynolds test — relevance without a propensity link, and 403 balancing — plus a strict limiting instruction.
Is propensity ever a valid purpose under 404(b)?
No. Propensity may support admission under M.R.E. 413 or 414 in sexual offense and child molestation cases, but it is never a proper basis under 404(b), and a military judge who admits evidence under 404(b) while reasoning from propensity has erred. When 404(b) evidence is admitted, members must be instructed on its narrow, limited purpose.
About the attorneys behind this guide
Michael Waddington, Civilian Military Defense Lawyer
Michael Waddington wrote this deep dive from more than 25 years of litigating uncharged misconduct — first offering it as an Army prosecutor, then beating it as a defense counsel and civilian military defense lawyer in courts-martial worldwide. A trial advocacy author and instructor, he teaches counsel to dismantle 404(b) evidence prong by prong, and his cross-examinations of the witnesses behind “other acts” allegations have repeatedly shown panels how thin the proof beneath a government pattern theory can be.
Alexandra González-Waddington, Founding Partner
Alexandra González-Waddington, founding partner of Gonzalez & Waddington, reviewed this page against 20-plus years of defending cases where 404(b) evidence was the government’s real theory — domestic violence prosecutions built on prior arguments, sexual offense cases importing decades-old allegations, and fraud cases papered with earlier bad paperwork. Her motions in limine pair the Reynolds framework with the specific dissimilarities that defeat pattern narratives, and she prepares clients for how uncharged allegations will be investigated and used.
Talk to a civilian court-martial defense lawyer today
Gonzalez & Waddington defends Soldiers, Sailors, Airmen, Marines, Guardians, and Coast Guardsmen worldwide — in UCMJ investigations, courts-martial, Article 15/NJP actions, GOMOR rebuttals, administrative separation boards, and Boards of Inquiry. We defend the whole case: the investigation, the trial, the administrative fallout, and the long-term consequences to your rank, retirement, clearance, and discharge.
Sources for this guide include the Uniform Code of Military Justice, the Manual for Courts-Martial (2024 ed.), the Rules for Courts-Martial, the TJAGLCS Criminal Law Deskbook, and the cited decisions of the Court of Appeals for the Armed Forces and the service Courts of Criminal Appeals. It is attorney advertising and general legal information — not legal advice, and reading it does not create an attorney–client relationship. Every case turns on its own facts. Service procedures vary; Army references (AR 27-10) are noted where used.