It Was an Accident: The Mental State in a PFMA Case

If someone was hurt by accident and no weapon was involved, that is not partner or family member assault (PFMA) under Montana law. The statute requires the State to prove that you acted purposely or knowingly. The only version that reaches negligence is causing bodily injury with a weapon. The hard part is that a judge or jury decides what your mental state was, largely from circumstances, not from what you say it was. This page is part of our Montana Domestic Violence Guide.

The Mental States in the PFMA Statute

MCA § 45-5-206(1) lists three versions of the offense, each with its own mental state:

• (a) purposely or knowingly causes bodily injury to a partner or family member;
• (b) negligently causes bodily injury to a partner or family member with a weapon;
• (c) purposely or knowingly causes reasonable apprehension of bodily injury in a partner or family member.

Montana's general rule is that a person is not guilty of an offense unless, with respect to each element, the person acted with one of the mental states of knowingly, negligently, or purposely (MCA § 45-2-103(1)). If the State cannot prove the mental state, it has not proved the offense.

How Montana Defines Each One

Notice that "knowingly" does not require that you wanted anyone to be hurt. For a result such as bodily injury, it is enough that you were aware it was highly probable your conduct would cause it. Our page on purposely, knowingly, and negligently covers these definitions in more depth.

What a True Accident Looks Like Legally

An accident is conduct where the result was neither your object nor something you were aware was highly probable. Examples that come up in real cases include a door opened into someone standing behind it, two people losing their balance while one tries to walk away, or an object dropped or knocked over during an argument.

Montana also defines an "involuntary act," which includes a reflex or convulsion and a bodily movement that is not a product of the effort or determination of the actor (MCA § 45-2-101(33)). A reflexive movement, such as pulling an arm away when grabbed, raises that issue.

Under MCA § 45-2-103(4), when a statute prescribes a mental state for the offense as a whole without distinguishing among the elements, it applies to each element. For PFMA under subsection (1)(a), that means the State has to connect the mental state to the bodily injury, not only to the fact that you moved.

How the State Proves Intent

MCA § 45-2-103(3) allows a mental state to be "inferred from the acts of the accused and the facts and circumstances connected with the offense." So the prosecutor will point to things like:

• what was said during the argument and right after the injury;
• the kind of injury and whether it matches the accident described;
• what you told the 911 dispatcher or the officer;
• whether you helped, called for help, or left; and
• in some cases, earlier incidents.

That last item deserves attention. Montana Rule of Evidence 404(b) bars evidence of other acts to show a person's character, but allows it for other purposes, and the rule lists "absence of mistake or accident" among them. Raising accident as a defense can therefore open an argument about whether earlier events come in. See prior acts evidence.

Negligence and the Weapon Version

Subsection (1)(b) is the exception to the purposely or knowingly requirement. It applies when bodily injury is caused negligently with a weapon. Criminal negligence is not ordinary carelessness. The risk disregarded must be of such a nature and degree that disregarding it is a gross deviation from the standard of conduct a reasonable person would observe, and "gross deviation" means a deviation considerably greater than lack of ordinary care (MCA § 45-2-101(43)).

A weapon is any instrument, article, or substance that, regardless of its primary function, is readily capable of being used to produce death or serious bodily injury (MCA § 45-2-101(79)). So an accident defense has to account for two questions when an object was involved: was it a weapon as defined, and was the handling of it grossly careless. Purposely or knowingly injuring someone with a weapon is a more serious charge, covered in assault with a weapon on a partner.

Alcohol Does Not Supply the Defense

A person may say he or she would never have done it sober, or does not remember. Under MCA § 45-2-203, an intoxicated condition is not a defense and may not be taken into consideration in determining the existence of a mental state, unless the defendant proves he or she did not know the substance was intoxicating. See alcohol and intoxication as a defense.

Building an Accident Defense

The evidence that supports an accident is physical and immediate: the layout of the space, photographs, the 911 recording, body camera video, and medical findings about how the injury was likely caused. Your own statements at the scene are part of that record, for better or worse.

If the defense will be that you did not have the required state of mind, the prosecutor must disclose rebuttal witnesses to that defense no later than 5 days before trial unless the court permits later (MCA § 46-15-322(6)). Your lawyer will also decide whether accident stands alone or alongside another of the PFMA defenses, such as a dispute about injury or fear.

Do not try to get the other person to confirm that it was an accident. If a no contact order is in place, that contact is a new offense, and it can be characterized as pressure on a witness.

This page explains Montana law in general as of the 2025 Montana Code Annotated. It is not legal advice about your specific case.