Mass. Gen. Laws ch. 22C § 24
If uniformed members of the state police in positions in the same rank are to be separated from such positions because of lack of work, lack of money or abolition of positions, said uniformed members shall be separated from such employment according to their seniority in such rank and shall be reinstated to such position in such rank according to such seniority, so that members senior in length of service in such rank shall be retained the longest and reinstated first. Uniformed members separated from positions pursuant to the provisions of this section shall be reinstated prior to the appointment of any other person under section ten, provided that the right to such reinstatement shall continue for no fewer than two years from the date of such separation and shall be subject to such rules and regulations as prescribed by the colonel.
Mass. Gen. Laws ch. 22C, § 24