Mont. Code Ann. § 10-3-606

If, following an enemy attack, the legislature or any state or local government council, board, or commission is unable to assemble a quorum as defined by the constitution of Montana or by statute, then those legislators or members of the council, board, or commission available for duty shall constitute the legislature, board, or commission and quorum requirements shall be suspended. Where the affirmative vote of a specified proportion of members for the approval of any action would otherwise be required, the same proportion of those voting thereon shall be sufficient.