Mont. Code Ann. § 61-9-405

Windshields required, exception – unobstructed and equipped with wipers – window tinting and sunscreening – restrictions – exemptions – definitions

(1) A motor vehicle, except a motorcycle, quadricycle, motor-driven cycle, or farm tractor, must be equipped with a front windshield meeting the requirements of 61-9-408, unless the driver wears safety glasses, goggles, or face shields at all times during the operation of the motor vehicle.

(2) A person may not drive a motor vehicle with:

(a) a sign, poster, substance, or other nontransparent material upon the front windshield, side wings, or side or rear windows of the vehicle that materially obstructs, obscures, or impairs the driver's clear view of the highway or an intersecting highway; or

(b) a windshield that is shattered or in such a defective condition that it materially impairs or obstructs the driver's clear view.

(3) The windshield on a motor vehicle must be equipped with a device for clearing rain, snow, or other moisture from the windshield. The device must be maintained in good working order.

(4) A person may not operate a motor vehicle that is required to be registered in this state upon a highway if:

(a) the windshield has sunscreening material that is not clear and transparent below the AS-1 line or if it has a sunscreening material that is red, yellow, or amber in color above the AS-1 line;

(b) the front side windows have sunscreening or other transparent material that has a luminous reflectance of more than 35% or has light transmission of less than 24%;

(c) the rear window or side windows behind the front seat have sunscreening or other transparent material that has a luminous reflectance of more than 35% or has light transmission of less than 14%, except for the rear window or side windows behind the front seat on a multipurpose vehicle, van, or bus; or

(d) the windows of a camper, motor home, pickup cover, slide-in camper, or other motor vehicle do not meet the standards for safety glazing material specified by federal law in 49 CFR 571.205.

(5) As used in 61-9-428, 61-9-429, and this section, the following definitions apply:

(a) "Glass-plastic glazing material" means a laminate of one or more layers of glass and one or more layers of plastic in which a plastic surface of the glazing faces inward when the glazing is installed in a vehicle.

(b) "Light transmission" means the ratio of the amount of total light, expressed in percentages, that is allowed to pass through the sunscreening or transparent material to the amount of total light falling on the motor vehicle window.

(c) "Luminous reflectance" means the ratio of the amount of total light, expressed in percentages, that is reflected outward by the sunscreening or transparent material to the amount of total light falling on the motor vehicle window.

(d) "Multipurpose vehicle" means a motor vehicle designed to carry 10 or fewer passengers that is constructed on a truck chassis or with special features for occasional off-road use.

(e) "Pickup cover" means a camper having a roof and sides but without a floor designed to be mounted on and removable from the cargo area of a pickup truck by the user.

(f) "Slide-in camper" means a camper having a roof, floor, and sides designed to be mounted on and removable from the cargo area of a truck by the user.

(g) "Sunscreening material" means a film, material, tint, or device applied to motor vehicle windows for the purpose of reducing the effects of the sun.

(6) Except as provided in subsection (7), subsection (4) applies to all vehicles that are equipped with tinted windows, including windows with less than 100% light transmission to which additional sunscreening material has been applied.

(7) Subsection (4) does not apply to a multipurpose vehicle that is equipped with tinted windows that were installed by the manufacturer of the vehicle or to a hearse, ambulance, government vehicle, or any other vehicle to which a currently valid certificate of waiver is affixed as specified under 61-9-428. A certificate of waiver must be issued by the department for a vehicle that was registered in this state on October 1, 1991, and was equipped with a sunscreening device or other material prohibited under subsection (4) on October 1, 1991.