N.J. Stat. § 40A:14-112
The board of chosen freeholders of a county, or the county park commissioners may, by resolution, provide that whenever any member of the county police department, county boulevard police system or county park police system shall be required to appear before any grand jury or at any municipal, County, Superior or Supreme Court proceeding, except in a civil action, the time during which he is so engaged shall be considered a time of assignment to, and performance of duty. When such appearance occurs during the member's assigned duty hours, he shall suffer no loss in compensation. When such appearance occurs outside his assigned duty hours he shall receive either compensatory time off from his regular duty hours or additional compensation.
N.J.S. § 40A:14-112