Montana Constitution Article IV § 7
Section 7. Ballot issues — challenges — elections. (1) An initiative or referendum that qualifies for the ballot under Article III or Article XIV shall be submitted to the qualified electors as provided in the Article under which the initiative or referendum qualified unless a new election is held pursuant to this section.
(2) A preelection challenge to the procedure by which an initiative or referendum qualified for the ballot or a postelection challenge to the manner in which the election was conducted shall be given priority by the courts.
(3) If the election on an initiative or referendum properly qualifying for the ballot is declared invalid because the election was improperly conducted, the secretary of state shall submit the issue to the qualified electors at the next regularly scheduled statewide election unless the legislature orders a special election.