Mont. Code Ann. § 3-10-512

If the office of a justice becomes vacant because of death or removal from the county or for any other cause before a successor is appointed, the docket and papers or electronically filed or stored documents that were in the justice's possession must be deposited in the office of some other justice in the county, who shall deliver them to the successor of the former justice. If there is no other justice in the county, the docket and papers or electronically filed or stored documents must be deposited in the office of the county clerk, who shall deliver them to the successor in office of the former justice.