It shall be unlawful to operate any flashing prewarning or warning signal light on any school bus except when the school bus is preparing to stop or is stopped on a highway for the purpose of permitting school children to board or alight from said school bus.
Prohibited Operation Of Special Lighting Equipment On School Buses
Mont. Code Ann. § 61-8-352, under Vehicle Operating Requirements.
Mont. Code Ann. § 61-8-352