When Montana police respond to a domestic call, they are deciding one main question in a short time: is there probable cause that someone committed partner or family member assault (PFMA) or a related offense, and if so, should that person be arrested now. State law pushes that decision toward arrest in certain situations, tells officers how to handle a scene where both people used force, and requires several other steps before they leave. This page walks through the sequence. It opens the police response section of our Montana Domestic Violence Guide.
If you are in danger right now, call 911. The National Domestic Violence Hotline is 1-800-799-7233.
The Legal Standard: Probable Cause
An officer does not need a warrant to arrest for PFMA. Under MCA § 46-6-311(1), a peace officer may arrest when the officer has probable cause to believe that a person is committing an offense, or has committed an offense and existing circumstances require immediate arrest. The statute adds that the summoning of an officer to a residence by a partner or family member "constitutes an exigent circumstance for making an arrest" (MCA § 46-6-311(2)(a)).
Probable cause is a lower standard than the proof beyond a reasonable doubt needed to convict. An arrest means an officer found enough to arrest. It is not a finding of guilt. What PFMA requires the State to proveis a separate question. The officer must also put the basis in writing: a PFMA charge must be supported by a peace officer's affidavit of probable cause (MCA § 45-5-209(3)).
When Arrest Is the "Preferred Response"
The same subsection says arrest is the preferred response in partner or family member assault cases involving:
- injury to the victim,
- use or threatened use of a weapon,
- violation of a restraining order, or
- other imminent danger to the victim.
The word is "preferred," and the general arrest power in subsection (1) says an officer "may" arrest. Our page on whether someone has to go to jail explains what that difference means in practice.
What Officers Look For
The statutes point officers to specific things. For the arrest decision: injuries, weapons, existing court orders, and present danger. Where both people appear to have used force, the officer must evaluate who the predominant aggressor is, based on prior history of violence, the relative severity of injuries, self-defense, relative size and strength, apparent fear, and witness statements (MCA § 46-6-311(2)(b)). We go through each one in the six predominant aggressor factors.
Officers may speak with each person separately, and the statute requires the notice of rights to the alleged victim to be given outside the other person's presence (MCA § 46-6-602). What you say during that conversation can be written into the report and used later. See talking to police at the scene.
What the Statutes Require at the Scene
| Step | What the law says | MCA |
|---|---|---|
| Arrest decision | An officer may arrest without a warrant on probable cause. Arrest is the preferred response in four listed situations. | § 46-6-311(1), (2)(a) |
| Mutual aggression | The officer evaluates who the predominant aggressor is, using six listed considerations. | § 46-6-311(2)(b) |
| Weapons | The officer must seize the weapon used or threatened to be used in the alleged assault. | § 46-6-603(1) |
| Notice to the other person | Outside the arrested person's presence, the officer gives notice of rights, shelters, and services. | § 46-6-602 |
| No contact order | If the court has a standing order, the officer serves it orally and in writing at the arrest or charge. | §§ 45-5-209(2), 46-6-311(3) |
| No arrest | The officer files a written report giving the reasons for the decision. | § 46-6-601 |
| Release | No release on bail until the person has appeared before a judge. | § 46-9-302(1) |
More detail on three of these rows: weapons seized at the scene, the victim rights notice, and the 72-hour no contact order.
Entry, Evidence, and Recordings
When a domestic call is to a home, it raises the question of when officers can come inside. Consent from an occupant, a warrant, and emergencies are the usual grounds, and each has limits. See police entering your home.
Evidence starts accumulating before officers arrive. The 911 call is recorded. At the scene there may be body camera footage, photographs, medical records, and written statements. The defense is entitled to request this material from the prosecutor under MCA § 46-15-322.
After the Arrest Decision
If there is an arrest, the person is taken to jail and must be brought before a judge without unnecessary delay (MCA § 46-7-101(1)). Because MCA § 46-9-302(1) bars release on bail before that appearance in partner or family member cases, a night or a weekend in custody is possible. A PFMA arrest can also be made at home at night, an exception to the usual rule for misdemeanors (MCA § 46-6-105). Our page on the first 48 hours picks up from there.
If there is no arrest at the scene, the matter is not necessarily over. A report goes to the prosecutor, and a charge can follow by warrant or summons. See arrested hours or days later.
Situations With Their Own Rules
Two situations have their own pages. One is when the person who called 911 is the one arrested. The other is when the accused is under 18, which moves the case into Youth Court: see juveniles and PFMA.
A&M Law is a Missoula firm that defends PFMA and other domestic violence charges in Western Montana. Our PFMA defense page describes that work.
This page explains Montana law in general as of the 2025 Montana Code Annotated. It is not legal advice about your specific case.