Law enforcement in Massachusetts
Many municipalities of Massachusetts have their own police departments, as do many colleges and universities. Though most county governments have been abolished, each county still has a Sheriff's Department which operates jails and correctional facilities and service of process within the county.
The Massachusetts State Police have statewide jurisdiction, including full criminal law enforcement, Highway Patrol and traffic enforcement, investigation, and special air, marine, and tactical response. They share concurrent jurisdiction with municipal and institutional departments, and have primary jurisdiction in towns that have no local police force. State police divisions ("Troops") are dedicated to the Massachusetts Turnpike and Logan International Airport, and since 1992 the state police have had primary responsibility for the state capital building, facilities of the Registry of Motor Vehicles, and DCR parks. State police also have sole authority under state law for investigating homicides, except for Boston, Worcester, and Springfield.
Though fully deputized in 175 cities and towns, Massachusetts Bay Transportation Authority Police have primary responsibility for MBTA facilities and commuter railroads statewide, and share enforcement duties (such as writing tickets for parking in bus stops) with local and state police, especially in remote areas and on Massport property. The Massachusetts Environmental Police  are also independent of the State Police.
A number of federal police agencies also operate in Massachusetts, subject to the limits and jurisdiction of federal law, including the Federal Bureau of Investigation and the Bureau of Alcohol, Tobacco, and Firearms.
- Devlin, Owen F. "MassHome Directory of Massachusetts Police Department Web Sites". www.masshome.com. Retrieved 2017-02-21.
- OLE (2016-09-08). "Massachusetts Environmental Police". Energy and Environmental Affairs. Retrieved 2017-02-21.
- "Firm News". Swartz & Swartz, P.C. Retrieved 2017-02-21.