Mass. Gen. Laws ch. 31 § 37
An appointing authority may grant a permanent employee a leave of absence or an extension of a leave of absence; provided that any grant for a period longer than fourteen days shall be given only upon written request filed with the appointing authority by such person, or by another authorized to request such leave on his behalf, and shall be in writing. The written request shall include a detailed statement of the reason for the requested leave and, if the absence is caused by illness, shall be accompanied by substantiating proof of such illness. A copy of the written grant shall be kept on file by the appointing authority, who shall, upon request, forward a copy thereof to the commission or administrator. No leave of absence for a period longer than three months, except one granted because of illness as evidenced by the certificate of a physician approved by the administrator, shall be granted pursuant to this paragraph without the prior approval of the administrator.
Any person elected to a state office or elected by the people to the office of mayor who is a permanent employee in a civil service position or is employed in a position in any public authority which is supported in whole or in part by public money shall, upon his written request made to the appointing authority, be granted a leave of absence without pay from his civil service position or from his position in such public authority for all or such portion of the term for which he was elected as he may at any time, or from time to time, designate, and shall not, as a result of such election, be suspended or discharged or suffer any loss of rights under the civil service law and rules.
Any person elected to a state office following appointment to a civil service position as a permanent employee who has not completed the statutory probationary period in such position shall, during such probationary period, upon his written request made to the appointing authority, be granted a leave of absence without pay from such position for all or for such portion of the term for which he was elected as he may designate within one month of his election to said office, and shall not, as a result of such election, be suspended or discharged or suffer any loss of rights under the civil service law and rules; provided that such person shall return to such position within one month of completion of the term or terms for which he was elected and that upon such return he shall complete the remaining portion of such probationary period. During such period such person shall be ineligible to take any promotional examination.
Any person who has been granted a leave of absence or an extension thereof pursuant to this section shall be reinstated at the end of the period for which the leave was granted and may be reinstated earlier. If the appointing authority, upon demand of such person, shall fail to reinstate him to his civil service position, such person may request a hearing before the administrator. The administrator shall proceed forthwith to hold such a hearing and to render his decision.
If a person shall fail to return to his civil service position at or before completion of the period for which a leave of absence has been granted under any provision of this section, the appointing authority shall, within fourteen days after the completion of such period, give such person a written notice setting forth the pertinent facts of the case and informing him that his employment in such position is considered to be terminated, whereupon the employment of such person in such position shall terminate. The appointing authority shall file with the administrator a copy of such notice which shall state the date on which the employment of such person should be recorded as having terminated. The provisions of sections forty-one through forty-five shall not apply to a termination made under this paragraph. Nothing in this section shall be deemed to prevent the subsequent reinstatement of such person pursuant to section forty-six.
Mass. Gen. Laws ch. 31, § 37