Reviewed and updated October 9, 2026 by the SearchSystems.net editorial team. The arrest counts are the ones each agency reported to the FBI, as the FBI held them on October 8, 2026. The jail figures are from the Vera Institute of Justice's Incarceration Trends data. Every office link was opened and checked against the office's own site between September 23, 2026 and October 4, 2026.
Mountainside, New Jersey, in Union County, has about 7,200 residents (2024 Census Bureau estimate). Every warrant for Mountainside comes from a judge of the Superior Court of New Jersey, Union County, is served by whichever agency finds the person, and is recorded in the court file of the case it was issued in. This guide says who issues and serves warrants here, where a person arrested on one is held, how to check for one and how one is cleared.
This guide covers who issues warrants, who serves warrants, after a warrant arrest, checking for a warrant, clearing a warrant and common questions.
Related guides: Mountainside public records, Union County warrants, Mountainside arrest records, Mountainside inmate search, Mountainside criminal records, Mountainside court records, New Jersey arrest records and New Jersey inmate search.
Who Issues Warrants in Mountainside
In New Jersey an arrest warrant is signed by a judge. For Mountainside that means the Superior Court of New Jersey, Union County, which hears every civil, criminal, family and probate case. A city with a municipal court of its own issues warrants on the tickets and ordinance cases it tries.
When a defendant misses a court date the judge issues a bench warrant, and either kind of warrant lives in the court file of the case, kept by the Superior Court Clerk and the County Clerk.
The court records page SearchSystems verified for the county is at njcourts.gov/public/find-a-case (page title: Find a Case), which answered when SearchSystems opened it on September 23, 2026.
Statewide, New Jersey Courts Public Access is the Judiciary's free online case search for civil and criminal cases.
Who Serves Warrants in Mountainside
The Union County Sheriff's Office and the agency that reports for Mountainside (filed by the FBI as Mountainside Police Department) serve warrants in and around Mountainside.
The FBI's agency list also places one campus police department, two other agencies and one state police unit in Union County (the arrest records guide names each one); each serves warrants on its own ground.
A warrant issued in Union County is good anywhere in New Jersey, so it is served by whichever agency finds the person, in a traffic stop as often as at the door.
Together, the 20 agencies in Union County with all twelve months of 2025 on file reported 5,391 arrests to the FBI that year; arrests on warrants are counted among them, not separately.
Each agency and what it reported is in Mountainside arrest records.
Where a Person Arrested on a Warrant from Mountainside Is Held
A person arrested on a warrant and kept in custody goes to the county jail, whichever agency made the arrest. The jail, run by the Union County Sheriff's Office, held about 330 people on an average day in 2020 by the Vera Institute of Justice's count and has a custody page SearchSystems verified at unioncountynj.org. The Mountainside inmate search guide covers the jail in full.
A person arrested in Mountainside on a warrant from another county is held at the same jail until that county takes custody.
How to Check for a Warrant in Mountainside
Whether a warrant is out from Mountainside shows in three places:
- The court file of the case, through the Superior Court Clerk and the County Clerk, since a warrant is recorded in the case it was issued in.
- New Jersey Courts Public Access, the Judiciary's free online case search for civil and criminal cases, for a case whose register of actions shows a warrant.
- The custody page of the Union County Sheriff's Office at unioncountynj.org, which shows people already arrested and booked, not open warrants.
The one Union County page SearchSystems verified, the court's, is not a list of open warrants.
The statewide criminal history kept by the New Jersey State Police is not open to the public in New Jersey, so it is not a route to a warrant check on someone else.
Clearing a Warrant from Mountainside
Only the judge who issued a warrant can recall it. For a case from Mountainside that means appearing before the Superior Court of New Jersey, Union County, with the case put back on the calendar through the Superior Court Clerk and the County Clerk.
Frequently Asked Questions
Can I check for a warrant online in Mountainside?
Not from the Union County pages SearchSystems verified; none of them is a warrant list. New Jersey Courts Public Access is the Judiciary's free online case search for civil and criminal cases, and a case whose register of actions shows a warrant is the record of it. The court file is the record of a warrant: ask the Superior Court Clerk and the County Clerk.
Who serves warrants in Mountainside?
The agency that reports for Mountainside inside the city and the Union County Sheriff's Office outside it, or whichever agency finds the person; an New Jersey warrant is valid anywhere in the state.
Where is a person arrested on a warrant in Mountainside held?
At the county jail, run by the Union County Sheriff's Office, if kept in custody.
How is a warrant from Mountainside cleared?
By appearing before the court that issued it; the judge recalls the warrant in court. The case is put back on the calendar through the Superior Court Clerk and the County Clerk.
Is this the official Mountainside website?
No. SearchSystems.net is an independent public records guide, online since 1997. It links to the official city, county, court and state offices described above and does not hold records, charge for them or take requests.