Mont. Code Ann. § 27-16-1002

Before an order of arrest can be made, the party applying shall prove to the satisfaction of the justice, by the affidavit of the party or some other person, the facts upon which the application is founded. The plaintiff shall also execute and deliver to the justice a written undertaking in the sum of $300, with sufficient sureties, to the effect that the plaintiff will pay all costs that may be adjudged to the defendant and all damages that the defendant may sustain by reason of the arrest, if the arrest is wrongful or without sufficient cause, not exceeding the sum specified in the undertaking.