N.J. Stat. Ann. § 40A:14-144

When any member or officer of the police department or force of any municipality is granted a leave of absence pursuant to any law authorizing the granting of leaves of absence to persons entering the military service of the United States, or of this State, the appointing authority may make a temporary appointment to the position held by said person and such temporary appointee shall not be obligated to contribute to any pension fund, nor shall he acquire any pension or tenure rights or civil service status.