Mass. Gen. Laws ch. 22C § 57
The colonel may appoint, at the request of the Massachusetts Society for the Prevention of Cruelty to Animals, the Berkshire Animal Protective Society, Inc., the Animal Rescue League of Boston, the Boston Work Horse Relief Association, the Lowell Humane Society, the Worcester Animal Rescue League or the Animal Rescue League of New Bedford, duly accredited agents of said corporations as special state police officers to serve for one year subject to removal by the colonel. Such special state police officers shall report to him relative to their official acts as such police officers at such times and in such manner as the colonel may require; provided, however, that such officers shall remain subject to the certification requirements of the Massachusetts Peace Officer Standards and Training Commission established in chapter 6E. They shall serve without pay, except their regular compensation as agents of said corporation. They shall receive no fees for services or return of any criminal process and shall have throughout the commonwealth the powers of constables and police officers to arrest and detain any person violating any law for the prevention of cruelty to animals.
Mass. Gen. Laws ch. 22C, § 57