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 Washington State, window tint laws are defined under RCW 46.37.430. The state allows a certain level of window tinting, measured by Visible Light Transmission (VLT). For passenger vehicles, the front side windows must allow more than 24% of light in, and the rear side and back windows must also allow more than 24% of light in. The front windshield may have a non-reflective tint on the top 6 inches. Reflective tints that reflect incoming light are restricted; the front and back side windows must not be more than 35% reflective. Washington State recognizes medical exemptions for drivers who require less light transmission due to a medical condition, and these individuals must carry documentation from a licensed physician. If a driver is cited for illegal window tint, it is considered a traffic infraction, which can be a 'fix-it ticket.' The driver must correct the violation within a specified period, pay a fine, and have the correction verified to potentially have the ticket dismissed. Failure to comply can result in additional fines and the infraction being recorded on the driver's record. Non-compliance with court directives may lead to further legal consequences, including the issuance of an arrest warrant.