Drivers who are driving in the shoulder (or 'breakdown lane') are ticketed for violating 89 4b (
Section 11B. Every person operating a bicycle upon a way, as defined in section one of chapter ninety, shall have the right to use all public ways in the commonwealth except limited access or express state highways where signs specifically prohibiting bicycles have been posted, and shall be subject to the traffic laws and regulations of the commonwealth and the special regulations contained in this section, except that: (1) the bicycle operator may keep to the right when passing a motor vehicle which is moving in the travel lane of the way, (2) the bicycle operator shall signal by either hand his intention to stop or turn; provided, however, that signals need not be made continuously and shall not be made when the use of both hands is necessary for the safe operation of the bicycle, and (3) bicycles may be ridden on sidewalks outside business districts when necessary in the interest of safety, unless otherwise directed by local ordinance. A person operating a bicycle on the sidewalk shall yield the right of way to pedestrians and give an audible signal before overtaking and passing any pedestrian.
If you are given a ticket for violating Chapter 89 Section 4B while riding your bicycle on a shoulder and being passed by faster motor vehicle traffic in the travel lane, what law are you going to cite that gives you the ability to violate Chapter 89 Section 4B? There aren't any in Massachusetts. You could argue that 89 11B gives you the ability to ride on a shoulder to pass slower traffic in the travel lane, but nowhere does it give you the ability to just travel on it.
Section 4B. Upon all ways the driver of a vehicle shall drive in the lane nearest the right side of the way when such lane is available for travel, except when overtaking another vehicle or when preparing for a left turn. When the right lane has been constructed or designated for purposes other than ordinary travel, a driver shall drive his vehicle in the lane adjacent to the right lane except when overtaking another vehicle or when preparing for a left or right turn; provided, however, that a driver may drive his vehicle in such right lane if signs have been erected by the department of highways permitting the use of such lane.