Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 89, § 8

When two vehicles approach or enter an intersection of any ways, as defined in section one of chapter ninety, at approximately the same instant, the operator of the vehicle on the left shall yield the right-of-way to the vehicle on the right. Any operator intending to turn left, in an intersection, across the path or lane of vehicles approaching from the opposite direction shall, before turning, yield the right-of-way until such time as the left turn can be made with reasonable safety. Any operator of a vehicle entering a rotary intersection shall yield the right-of-way to any vehicle already in the intersection. The foregoing provisions of this section shall not apply when an operator is otherwise directed by a police officer, or by a traffic regulating sign, device or signal lawfully erected and maintained in accordance with the provisions of section two of chapter eighty-five and, where so required with the written approval of the department of highways and while such approval is in effect.

At any intersection on ways, as defined in section one of chapter ninety, in which vehicular traffic is facing a steady red indication in a traffic control signal, the driver of a vehicle which is stopped as close as practicable at the entrance to the crosswalk or the near side of the intersections or, if none, then at the entrance to the intersection in obedience to such red or stop signal, may make either (1) a right turn or (2) if on a one-way street may make a left turn to another one-way street, but shall yield the right-of-way to pedestrians and other traffic proceeding as directed by the signal at said intersection, except that a city or town, subject to section two of chapter eighty-five, by rules, orders, ordinances, or by-laws, and the department of highways on state highways or on ways at their intersections with a state highway, may prohibit any such turns against a red or stop signal at any such intersection, and such prohibition shall be effective when a sign is erected at such intersection giving notice thereof. Any person who violates the provisions of this paragraph shall be punished by a fine of not less than thirty-five dollars.