Mont. Code Ann. § 61-8-338
(1) Except as provided in subsection (2), all signals required in this part that are given by hand and arm must be given from the left side of the vehicle by the operator of the vehicle in the following manner:
History: En. Sec. 66, Ch. 263, L. 1955; R.C.M. 1947, 32-2169; amd. Sec. 5, Ch. 450, L. 1983; amd. Secs. 20, 51(2)(b), Ch. 352, L. 2003.