N.J. Stat. § 4:5-106.16: Imprisonment upon failure to pay judgment

If judgment is rendered for the plaintiff the court shall cause a defendant who shall fail to pay forthwith the amount of the judgment rendered against him, and all costs and charges incident thereto, to be committed to the county jail until the judgment is paid but no such imprisonment shall exceed 30 days in the case of the first offense or 90 days for a second or subsequent offense.

L.1957, c. 140, p. 537, s. 16.