Partner or family member assault is not a strict liability offense. Each of its three forms names a mental state: two require that the accused acted purposely or knowingly, and one requires that the accused acted negligently and caused the injury with a weapon (MCA § 45-5-206(1)). If the State cannot prove the required mental state, it has not proved PFMA. This page is part of our Montana Domestic Violence Guide.
Which Mental State Goes With Which Form
- § 45-5-206(1)(a): purposely or knowingly causes bodily injury to a partner or family member.
- § 45-5-206(1)(b): negligently causes bodily injury to a partner or family member with a weapon.
- § 45-5-206(1)(c): purposely or knowingly causes reasonable apprehension of bodily injury in a partner or family member.
Montana law requires a mental state for each element of an offense unless the offense is one of absolute liability (MCA § 45-2-103(1)). When a statute prescribes a mental state for the offense as a whole, that mental state applies to each element (§ 45-2-103(4)).
The Three Definitions
| Mental state | Meaning | MCA |
|---|---|---|
| Purposely | It is the person's conscious object to engage in the conduct or to cause the result. | § 45-2-101(65) |
| Knowingly (as to a result) | The person is aware that it is highly probable that the result will be caused by the person's conduct. | § 45-2-101(35) |
| Negligently | The person consciously disregards a risk that the result will occur, or disregards a risk the person should be aware of, and doing so is a gross deviation from what a reasonable person would do. | § 45-2-101(43) |
PFMA is defined by its result: bodily injury, or apprehension of bodily injury. So in plain terms, purposely means you meant to cause that result. Knowingly means you were aware it was highly probable your conduct would cause it, even if causing it was not your goal.
Negligence and the Weapon Subsection
Criminal negligence is not ordinary carelessness. The statute says the risk "must be of a nature and degree that to disregard it involves a gross deviation from the standard of conduct that a reasonable person would observe in the actor's situation," and it defines gross deviation as one "considerably greater than lack of ordinary care" (MCA § 45-2-101(43)).
In the PFMA statute, negligence is enough only when the injury was caused with a weapon. 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" (§ 45-2-101(79)). That is a broad definition, and it is not limited to guns and knives.
When the State says a weapon was used purposely or knowingly to cause bodily injury, the charge is more likely to be the separate offense of assault with a weapon, which carries up to 20 years in state prison (MCA § 45-5-213).
Why an Accident Is Not PFMA
Put the three subsections together and a gap appears on purpose. An injury caused without a weapon is PFMA only if it was caused purposely or knowingly. Careless, clumsy, or unlucky conduct that hurts a family member does not fit, because negligence without a weapon is not in the statute.
Two cautions. First, "I did not mean to hurt anyone" is not the same as an accident under these definitions. A person who did not want to cause injury, but was aware it was highly probable, acted knowingly. Second, saying it was an accident does not end the case. The State may argue otherwise, and a judge or jury decides which account the evidence supports. Our page on accident as a defense goes further.
How a Mental State Is Proved
Nobody can see into another person's mind, and the law does not ask the State to try. A mental state "may be inferred from the acts of the accused and the facts and circumstances connected with the offense" (MCA § 45-2-103(3)). The evidence usually includes:
- What happened immediately before and after.
- The nature and location of any injury.
- Statements made to the 911 dispatcher and to officers by everyone involved.
- Body camera video and photographs.
- Messages sent before or after the incident.
Your own statements are often the State's main evidence of intent. That is one reason lawyers advise people to be careful about talking to police at the scene, and to say nothing about the case to the other person, especially while a no contact order is in effect.
Intoxication and Other Common Questions
People often ask whether being drunk, being provoked, or reacting in the moment changes the mental state. Those are separate legal questions with their own rules. See alcohol and intoxication as a defense and self-defense in a PFMA case.
The mental state element is where many PFMA cases are contested, and it is rarely obvious from a citation alone which way the evidence points. A&M Law defends these charges in Western Montana. Our PFMA defense page explains how we start.
This page explains Montana law in general as of the 2025 Montana Code Annotated. It is not legal advice about your specific case.