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 California, window tint laws are defined in the California Vehicle Code, specifically in sections 26708 and 26708.5. These laws regulate the amount of visible light transmission (VLT) and visual light reflection (VLR) allowed for vehicle windows. In California, the front side windows must allow more than 70% of light in (70% VLT), while the back side windows and rear window can have any darkness if the vehicle has outside rearview mirrors on both sides. The front windshield can only have non-reflective tint on the top 4 inches. The VLR must not be more than a certain percentage to reduce glare and reflection. California does recognize medical exemptions for individuals who require darker tints due to medical conditions, and these individuals must carry a letter certifying the medical necessity from a licensed physician. Violations of window tint laws are typically considered 'fix-it' tickets, meaning they are correctable violations. If corrected within the allotted time, a small fee is paid, and an authorized person (such as a police officer) verifies the correction, the court may dismiss the ticket. Failure to comply can result in fines, additional tickets, and potentially a warrant for arrest if court dates are missed or fines are unpaid.