Mass. Gen. Laws ch. 41 § 112
In towns and regional school districts in which the provisions of chapter thirty-one and the rules governing the civil service have not been applied to the labor service, the city councils, the selectmen and the regional district school committees shall take any necessary action to secure the employment of veterans, as defined in clause Forty-third of section seven of chapter four, in the labor service of their respective cities, towns and districts in preference to all other persons.
In regional school districts in which the provisions of said chapter thirty-one and the rules governing the civil service have not been applied to custodian and janitorial services, the regional district school committees shall take any necessary action to secure the employment of veterans, as so defined, in preference to all other persons.
The second paragraph of this section shall take effect in a regional school district upon its acceptance by vote of the regional district school committee.
Mass. Gen. Laws ch. 41, § 112