Mass. Gen. Laws ch. 30 § 9H
Any employee of the commonwealth, who is a veteran as defined in clause Forty-third of section seven of chapter four or is a member of a department of war veterans listed in section seventeen of chapter eight, and who desires to participate in a Veterans Day or Memorial Day exercise, parade or service, shall be granted a reasonable and sufficient period of time off from his duties to attend and participate in such services or exercises.
This section shall not apply to employees whose services are essential and critical to public health or public safety, including but not limited to those employees whose regular and major duties require them to have the care, custody, instruction or supervision of inmates in correctional facilities and institutions or of persons who are mentally ill or mentally defective or defective delinquents, firefighters, police officers, guards and other persons who are determined to be essential and critical to the effective delivery of public services to the commonwealth. Any time off taken by an employee of the commonwealth under this section shall be without pay; provided, however, that any such employee may elect to apply accrued vacation or personal leave time to such time off.
Mass. Gen. Laws ch. 30, § 9H