In a Montana partner or family member assault (PFMA) trial, the State generally cannot use past incidents to argue that you are a violent person and so must have done it this time. Past incidents between the same two people can still come in if the judge finds they prove something specific, such as intent or the absence of an accident, and that the jury can hear them without unfair prejudice. This page explains the rules that decide that. It is part of our Montana Domestic Violence Guide.
The Starting Rule: No Character Evidence
Montana Rule of Evidence 404(a) says evidence of a person's character or a trait of character is not admissible to prove that the person acted in conformity with it on a particular occasion. Rule 404(b) applies that idea to specific events: "Evidence of other crimes, wrongs, or acts is not admissible to prove the character of a person in order to show action in conformity therewith."
The rule exists because this kind of evidence is powerful. A jury that hears about an earlier incident may convict on the history instead of on proof of the charged event.
The Other Purposes Listed in Rule 404(b)
The rule continues: other acts evidence "may, however, be admissible for other purposes, such as proof of motive, opportunity, intent, preparation, plan, knowledge, identity, or absence of mistake or accident." The words "such as" mean the list gives examples.
This is where most of the argument happens in a domestic case. A prosecutor may say an earlier incident shows motive or intent. The defense may respond that the stated purpose is only a relabeled character argument, that the earlier event is too different or too old to prove anything, or that the issue it supposedly proves is not actually disputed.
| Why the evidence is offered | Result | Source |
|---|---|---|
| To show you are a violent person, so you probably did it this time | Not allowed | Rule 404(a) and the first sentence of Rule 404(b) |
| To prove motive, intent, plan, knowledge, identity, or absence of mistake or accident | May be allowed, if that issue is genuinely in dispute | Rule 404(b), second sentence |
| Any purpose, where the risk of unfair prejudice substantially outweighs the value | May be excluded by the judge | Rule 403 |
| To rebut evidence of good character that the defense chose to offer | May be allowed | Rule 404(a)(1) |
Rule 403: The Balancing Test
Passing Rule 404(b) is not the end. Under Rule 403, relevant evidence "may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury." A judge can admit part of an incident and exclude the rest, or limit how it is described. How a particular judge will strike that balance cannot be predicted from the rule alone.
How Your Defense Can Open the Door
The purposes in Rule 404(b) are tied to what is contested at trial, so the defense theory affects what the State can offer.
- Accident. "Absence of mistake or accident" is a listed purpose. If the defense is that an injury was accidental, the State may argue an earlier incident rebuts that. See it was an accident.
- Good character. An accused person may offer evidence of a pertinent trait of their own character, but the prosecution may then rebut it (Mont. R. Evid. 404(a)(1)). The defense must give written notice of an intention to offer good character evidence within 30 days after arraignment (MCA § 46-15-323(2)).
- Self-defense. Evidence about the other person's character can be offered by the accused under Rule 404(a)(2), and the prosecution may rebut it. See self-defense in a PFMA case.
These are strategic decisions with real trade-offs. They should be made with a lawyer who has read the whole file.
Notice and Timing
Montana's Rule 404(b) does not contain a notice requirement in its text, and the statute that once required notice of other acts evidence, MCA § 46-13-109, was repealed in 2011. That does not mean the evidence arrives as a surprise. On request, the prosecutor must make available the names and statements of the witnesses the State may call and the documents and objects it may use at trial (MCA § 46-15-322(1)(a) and (d)). See discovery in a PFMA case.
Objections that can be decided before trial are to be raised at or before the omnibus hearing (MCA § 46-13-101(1)). A defense lawyer who sees earlier incidents in the police reports will usually ask the court to rule on them ahead of trial so the jury never hears evidence that should have been kept out.
Prior Convictions at Sentencing Are Different
Do not confuse trial evidence with sentencing. The PFMA statute raises the penalty for a second offense and again for a third or subsequent offense, and it lists which earlier convictions count (MCA § 45-5-206(3)(a) and (b)). That is decided by the judge, and it does not depend on Rule 404(b). Our pages on how prior convictions count and the PFMA penalties chart cover that side.
Other evidence disputes in these cases, such as earlier statements by a witness who does not testify, follow separate rules. See when the other person recants or will not testify.
This page explains Montana law in general as of the 2025 Montana Code Annotated and the Montana Rules of Evidence. It is not legal advice about your specific case.