Mont. Code Ann. § 3-1-608

In the event of a failure to resign, the office of chief justice, associate justice, or district judge automatically becomes vacant and the former occupant has no further right, power, or authority therein for any purpose and no right to any emoluments thereof, notwithstanding the fact that a successor is not appointed or elected. The vacancy becomes operative to deprive the person of the emoluments of the office in order to carry out the policy of this section and 3-1-607.