Three of the following defunct Commonwealth of Massachusetts police agencies (Registry of Motor Vehicles Division of Law Enforcement, Massachusetts Capitol Police, Metropolitan District Commission Police) were merged in 1992 by Chapter 412 of the Massachusetts Acts of 1991 along with the former Department of Public Safety - Division of State Police to form the current Department of State Police. All officers of the three departments became Massachusetts State Troopers at the time of the merger without needing to attend the Massachusetts State Police Academy.
Boston Municipal Police
The Boston Municipal Police were founded in 1979 and had full city-wide police powers in the City of Boston as Special Police Officers. However, the officers of the department were primarily tasked with patrol of city buildings and public property as well as responding to security alarms. The department was dissolved on January 1, 2007 and replaced by the Boston Municipal Protective Services, an unarmed security force. Officers of the Municipal Protective Services still hold arrest powers as Special Police Officers but the vast majority of law enforcement activity previously handled by the Boston Municipal Police is now the responsibility of the Boston Police Department.
Department of Public Safety - Division of State Police
This is the former statewide police department for the Commonwealth of Massachusetts, which was founded in 1865; the M.D.C. Police, Registry of Motor Vehicles Police, and Capitol Police merged with this department to form the new Department of State Police in 1992. Prior to being known as the Massachusetts State Police, the department was known as the Special District Police of Massachusetts from 1879 to 1919.
Registry of Motor Vehicles Division of Law Enforcement
The Registry Police had the primary function of enforcing motor vehicle safety laws statewide, drivers license testing, crash investigation, enforcing laws & regulations on Registry property, and commercial vehicle inspection, although that had full police powers statewide.
Inspectors of the Registry Police were unique in the fact that as Registry employees they were able to suspend an operator's license on the roadside.
The Registry Police Statewide HQ was located at 100 Nashua St., Boston.
Massachusetts Capitol Police
The Capitol Police had the primary function of law enforcement on the grounds and adjacent streets of the State Capitol and all state property. The Capitol police provided vehicle cruiser, motorcycle and traffic patrols, criminal investigations and executive protection services. The Capitol Police station was at 1 Ashburton Place in Government Center and became MSP Barracks H-1.
Metropolitan District Commission Police
The Metropolitan District Commission's Police Department; the Massachusetts Metro Police was created in 1893. The Metropolitan Police had the primary jurisdiction of law enforcement on all MDC controlled properties, roadways and all Massachusetts Water Resources Authority (MWRA) facilities, Reservoirs and Watersheds. Additionally, the MDC Police had patrol jurisdiction on US Route 1 in Chelsea and Revere, Interstate 93 in Boston and Milton (Central Artery and the Southeast Expressway). MDC Police also had full jurisdiction in cities and towns wherever there were MDC facilities or property.
MDC Police were the third largest police agency in New England with over six hundred officers working primarily throughout Metropolitan Boston. They were commonly referred to as The Mets. In addition to patrol functions The Mets provided tactical assistance to area cities and towns in the form of regional SWAT teams, the Marine Unit and tactical operations units. Examples include Tactical Officers assigned to the city of Boston during court ordered school desegregation, assignment as the primary security agency for the Department of State with the responsibility of providing security and escorts for visiting dignitaries and annual assignments to assist cities and towns during the Boston Marathon.
MDC Police also maintained a full service detective unit to investigate crimes on its primary jurisdiction as well as providing Detectives and undercover agents to area cities and towns, area Drug Task Forces, the (state) Governor's Auto Theft Strike Force, the DEA Boston Drug Task Force, the Secret Service and the FBI.
The last chief of the MDC Police was former Boston Police Commissioner William J. Bratton, who later was NYPD Commissioner and Los Angeles Police Department chief.