All states have traffic laws that limit the amount of window tint on motor vehicles—often by specifying the amount of visible light transmission (VLT) that is required. VLT is the amount of light that is transmitted through the window and into the vehicle. For example, a 70%VLT means that 70% of light will pass through the window and 30% will be reflected. Thus, a lower VLT indicates a darker film or tint.

Another term to know is visual light reflection (VLR)—which is the opposite of VLT. VLR is the amount of solar energy that is reflected off the glass and away from the inside of the vehicle.

In most states tickets or citations for illegal window tint are known as fix-it tickets and the ticket or citation will indicate that it is a correctable violation of traffic laws. For example, if you fix the window tint problem within the required period, pay a small fine, and get the signature of an authorized person (a local police officer) the court may dismiss the ticket.

But if you fail to fix the window tint problem within the required period you must pay the fine for the violation and you may be issued another ticket that will be part of your driving record. And if you fail to pay the ticket or appear in court on the hearing date the court may issue a warrant for your arrest.

Window tint laws vary from state to state and some states have exemptions for certain vehicles such as limousines and recognize medical exemptions when the driver has a written statement from a licensed medical doctor, ophthalmologist, or optometrist.

In Maine, window tint laws are regulated under Title 29-A, Section 1916 of the Maine Revised Statutes. The law specifies the amount of light that must pass through the window film (VLT) and varies depending on the window's location on the vehicle. For example, the front side windows must allow more than 35% of light in, while the back side and rear windows can have any level of darkness if the vehicle has outside rearview mirrors on both sides. The law also regulates the reflectiveness of the tint, with a specification that no window tint can be more than 35% reflective, addressing the VLR aspect. Maine recognizes medical exemptions for individuals who require a lower VLT due to medical conditions, and these individuals must carry documentation from a licensed physician. If a driver is cited for illegal window tint in Maine, it is considered a traffic infraction, which can be corrected. The driver would need to remove or replace the non-compliant tint, pay a fine, and have the correction verified by an authorized person, such as a local police officer, to potentially have the ticket dismissed. Failure to correct the violation or to pay the fine can result in additional penalties, including the possibility of a warrant for arrest if the court's requirements are not met.