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http://www.mass.gov/legis/laws/mgl/90-13a.htm
PART I. ADMINISTRATION OF THE GOVERNMENT
TITLE XIV. PUBLIC WAYS AND WORKS
CHAPTER 90. MOTOR VEHICLES AND AIRCRAFT
MOTOR VEHICLES
Chapter 90: Section 13A. Seat belt use required; exemptions; penalty
Section 13A. No person shall operate a private passenger motor vehicle or ride in a private passenger motor vehicle, a vanpool vehicle or truck under eighteen thousand pounds on any way unless such person is wearing a safety belt which is properly adjusted and fastened; provided, however, that this provision shall not apply to:
(a) any child less than twelve years of age who is subject to the provisions of section seven AA;
(b) any person riding in a motor vehicle manufactured before July first, nineteen hundred and sixty-six;
(c) any person who is physically unable to use safety belts; provided, however, that such condition is duly certified by a physician who shall state the nature of the handicap, as well as the reasons such restraint is inappropriate; provided, further, that no such physician shall be subject to liability in any civil action for the issuance or for the failure to issue such certificate;
(d) any rural carrier of the United States Postal Service operating a motor vehicle while in the performance of his duties; provided, however, that such rural mail carrier shall be subject to department regulations regarding the use of safety belts or occupant crash protection devices;
(e) anyone involved in the operation of taxis, liveries, tractors, trucks with gross weight of eighteen thousand pounds or over, buses, and passengers of authorized emergency vehicles.
[ Clause (f) of first paragraph added by 2008, 225 effective October 29, 2008.]
(f) the side facing seat on which the factory did not install a seat belt in any car owned for the purpose of antique collection.
Any person who operates a motor vehicle without a safety belt, and any person sixteen years of age or over who rides as a passenger in a motor vehicle without wearing a safety belt in violation of this section, shall be subject to a fine of twenty-five dollars. Any operator of a motor vehicle shall be subject to an additional fine of twenty-five dollars for each person under the age of sixteen and no younger than twelve who is a passenger in said motor vehicle and not wearing a safety belt.
The provisions of this section shall be enforced by law enforcement agencies only when an operator of a motor vehicle has been stopped for a violation of the motor vehicle laws or some other offense.
Any person who receives a citation for violating this section may contest such citation pursuant to section three of chapter ninety C. A violation of this section shall not be considered as a conviction of a moving violation of the motor vehicle laws for the purpose of determining surcharges on motor vehicle premiums pursuant to section one hundred and thirteen B of chapter one hundred and seventy-five.