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 Oregon, window tint laws are regulated under ORS 815.221, which specifies the amount of light that must pass through vehicle windows, known as Visible Light Transmission (VLT). Oregon law requires that the front side windows must allow more than 35% of light in. The back side and rear windows can have any tint darkness. The law also specifies that the front windshield may only have tint on the top 6 inches. Reflective tint is allowed for the front side and back side windows but must not be more than 13% reflective. The VLT is a measure of how much light is allowed through the tint film, with a lower VLT indicating a darker tint. Oregon recognizes medical exemptions for individuals who require a darker tint due to medical conditions, and these individuals must carry documentation signed by a licensed physician. Violations of the window tint laws can result in a 'fix-it ticket,' which is a correctable violation. If corrected within a specified period and verified by an authorized person, such as a local police officer, the court may dismiss the ticket. Failure to correct the violation or to pay the fine can lead to additional tickets and potential warrants for arrest if court appearances are missed.