Maine Window Tint Limit: 35% Light Transmittance and a State Police Certificate

The operative Maine rule is 29-A MRS §1916, "Reflective and tinted glass," and it binds two people at once: a driver may not operate a motor vehicle required to be registered in Maine, and an inspection mechanic may not issue a certificate of inspection, if any of the four conditions in subsection 1 is met. Those are a reflective window (paragraph A), a windshield treated so that it passes less light than the original or an original replacement windshield (paragraph B), a side or rear window passing less than 35% light transmittance net of glass and material (paragraph C), and a windshield, front door window or window at either end of a rear passenger seat that is not 2-way glass giving the occupants a clear view out and a person outside a clear view of the occupants and the interior (paragraph D). The 35% figure was set by PL 2007, c. 186, §1; the current text is the version the Revisor's Office publishes as current through October 1, 2025.

Subsection 2 is a closed list of exceptions and it is short. Subsection 1 does not reach a certificate or other paper the law requires or allows to be displayed, the manufacturer's suggested retail price label, or sun-screening and window-tinting material above the AS-1 line in the top portion of the windshield. Where the windshield carries no AS-1 line, the permitted strip is measured instead: 5 inches from the top. Maine defines the AS-1 line in the statute itself as the marking bearing the letters "AS," the number "1" and an arrow required on certain safety glazing under 49 CFR §571.205 (2006). Separately, paragraph B of subsection 2 lifts the 35% rule and the 2-way glass rule for side windows behind the operator's seat and for the rear window, but only if the vehicle carries two outside rear view mirrors, one on each side, adjusted for a clear view of the highway behind. A vehicle with limousine-dark rear glass and only one exterior mirror therefore fails, even though the same glass on a two-mirror vehicle passes.

Maine also runs a medical route rather than a blanket exemption. Under §1916(2)(A)(4) the Chief of the State Police may grant an exception where sunlight adversely affects the health of the owner or of a person who usually occupies the vehicle, and on a proper application will issue the owner a certificate of exemption that must be produced when a law enforcement officer asks for it.

The certificate scheme in subsection 3 is what makes Maine unusual. The owner or operator of a vehicle whose tinted windows were not replaced in accordance with Federal Motor Vehicle Safety Standard 205, or whose windows are covered by or treated with tinting material, must acquire a light transmittance certificate and show it to the inspection mechanic at the time of inspection. The Chief of the State Police authorizes who may examine glazing and issue certificates; the Bureau of State Police supplies the certificates on request and they remain the property of the State. An authorized issuer who is adjudicated of a §1916 violation, or who files an answer of "not contested," must return every unissued certificate to the Bureau within 10 days, and the Bureau may not supply that person with certificates for 6 months.

The metering itself happens at the installer, not in the inspection lane. The Bureau of State Police rule for aftermarket tinting, 16-222 CMR ch. 12, effective September 30, 1990, requires the installer to measure visible light transmittance with a light meter accurate to plus or minus 3%, to test an untreated window first as a baseline, and to refuse a certificate of compliance where the final application combined with factory tinting made to FMVSS 205 transmits less than 35% of visible light. Installers buy the certificate forms from the State Police Traffic Division at $5.00 per pad of 100, must keep a copy of every certificate issued for three years, must produce those records to any full-time law enforcement officer during normal business hours, and must forward all copies to the Traffic Division if the business closes. Note that this rule still carries an authority line to former 29 MRSA §1369-A, the predecessor of Title 29-A.

At the annual inspection, the Maine Motor Vehicle Inspection Manual (16-222 CMR ch. 1) directs the technician to reject a vehicle if any window is composed of, covered with or treated with reflective material, if the windshield carries tint that is not part of a factory original windshield built to FMVSS 205 (a tinted sunshield strip extending no more than 5 inches from the top is permissible), and if the owner of a tinted vehicle cannot produce a certificate of compliance approved by the Bureau of the Maine State Police. The manual's own note exempts vehicles with tinted glass on the rear side windows and rear window from that certificate demand, and requires any failing film to be removed. So the inspection check is documentary rather than a meter reading, which is why the certificate matters more in Maine than the film's brand or shade name.

A §1916 violation is a traffic infraction and the statute fixes a floor rather than a ceiling: subsection 6 says a person adjudicated of a violation must be punished by a forfeiture of not less than $100. Subsection 4 lists seven separate ways to violate, and most of them target installers, not drivers: installing a replacement window or tinting film that fails subsections 1 and 2; failing to issue a certificate after installing tint for compensation; altering the film after a certificate issued and then displaying that certificate as proof of compliance; displaying a light transmittance certificate known to be fictitious, issued to another vehicle, or issued to a noncompliant vehicle; knowingly causing a certificate to issue for a noncompliant vehicle; operating or causing the operation of a noncompliant vehicle; and failing to return unissued certificates to the Bureau of State Police.

Subsection 5 shifts the burden at the roadside: if the operator of a vehicle with a tinted replacement window or tinting material installed cannot produce the certificate when a law enforcement officer asks, it is presumed that the vehicle does not meet §1916. An authorized certificate issuer who is adjudicated loses access to certificates for 6 months. Separately, a failing vehicle will not receive an inspection sticker, and the inspection manual requires the tinting treatment or covering to be removed before the vehicle can pass.