Mont. Code Ann. § 44-11-302

It is the purpose of this part to permit one or more law enforcement agencies of this state to enter into mutual aid agreements, on the basis of mutual advantage, with one or more law enforcement agencies of any other state or the United States in order to facilitate and coordinate efficient, cooperative enforcement efforts directed at mutual law enforcement problems transcending jurisdictional boundaries and to insure the prompt and effective delivery of law enforcement and emergency services in areas that, due to geographic remoteness, population sparsity, and economic and other factors are in need of an increased law enforcement presence.