With proven litigation skills and previous experience as a New Jersey Deputy Attorney General, Jeff Mongiello represents clients in commercial disputes, white-collar criminal matters, and appellate litigation. He also assists his clients, which include health care, dietary supplement, financial services, technology, media, and telecommunications companies, with their confidential internal investigations.

Jeff has extensive experience representing clients in white-collar criminal and civil government investigations, ranging from fraud to public corruption. Additionally, he litigates a wide variety of commercial cases, including contractual disputes, insurance coverage disputes, fraud, and class actions, in state and federal court. Jeff is also an experienced and accomplished appellate lawyer, having prosecuted and defended appeals in federal circuit courts of appeal and state appellate courts.

Earlier in his career, Jeff served as Deputy Attorney General in the New Jersey Attorney General’s Office, Division of Criminal Justice – Appellate Bureau. In that role, he represented the State before the New Jersey Appellate Division and Supreme Court in high-profile matters. He also successfully defended against a constitutional challenge in the New Jersey Supreme Court to the state’s judicial recall statute, which authorizes retired judges over the age of 70 to temporarily return to service. In 2015, Jeff received the Attorney General’s Award for Excellence in Trial Litigation for his role in a successful public corruption prosecution by twice securing reversals on interlocutory appeals of the trial court’s rulings, including one reversal on an emergent basis during trial to prevent the court from issuing its proposed jury charge.


  • Defended a dietary supplement company in a federal class action claim that alleged false labeling and advertising of the company’s products.
  • Represented a health care communications company in an investigation and litigation relating to whether promotional product materials were educational in nature and in compliance with federal law.
  • Defended directors and officers of a health care services company in litigation brought by a manufacturer alleging fraudulent practices in the sale of a product.
  • Obtained a clemency order in a district court releasing from incarceration a client with heightened COVID-19 risk factors.
  • Obtained a reinstatement of the client’s claims before the U.S. Court of Appeals for the Second Circuit after the district court had dismissed the lawsuit.
  • Drafted a successful Petition for Certification to the New Jersey Supreme Court that convinced the court to review a published decision by the Appellate Division that had allowed the plaintiff to pursue claims against a client under New Jersey’s Law Against Discrimination.
  • Drafted a brief in a contractual dispute where the New York Appellate Division affirmed a declaratory judgment, entered after a bench trial, that an insurance company client was entitled to reimbursement plus interest.
  • Successfully moved before the New Jersey Appellate Division to dismiss an appeal as improvidently filed, persuading the Appellate Division that the trial court’s order remanding the matter back to the board was not a final appealable judgment pursuant to Rule 2:2-3.
  • Seton Hall University School of Law (J.D., magna cum laude, 2011)
    • Managing Editor, Seton Hall Law Review
    • Order of the Coif
    • Distinguished Scholar
  • University of Maryland (M.P.P., 2006)
  • University of Maryland (B.A., 2005)
  • The Honorable Anne M. Patterson of the New Jersey Supreme Court
  • The Honorable Mary L. Cooper of the U.S. District Court for the District of New Jersey
  • The Best Lawyers in America©: “Ones to Watch,” Commercial Litigation (2021)
  • Appointed twice by the New Jersey Supreme Court to serve as a member of the District VI (Hudson County) Ethics Committee (2017 to 2021; 2021 to present)
  • New Jersey Attorney General’s Award for Excellence in Trial Litigation (2015)
Bar Admissions
  • New Jersey
  • New York
Court Admissions
  • U.S. Court of Appeals for the Third Circuit
  • U.S. District Court, District of New Jersey
  • U.S. District Court, Eastern District of New York
  • U.S. District Court, Southern District of New York
  • New Jersey State Bar Association
    • Appellate Practice Committee
  • American Bar Association
    • Criminal Justice Section, White Collar Crime Committee
      • Corporate Criminal Liability Subcommittee
      • Health Care Fraud Subcommittee
      • Financial Institution Fraud/Money Laundering and Patriot
    • Litigation Section
    • Business Law Section
      • Business Crimes, Investigations and Corporate Compliance
  • National Association of Criminal Defense Lawyers
  • Association of Criminal Defense Lawyers of New Jersey
  • Food and Drug Law Institute
  • American Health Law Association
  • District VI (Hudson County) Ethics Committee
  • John C. Lifland American Inn of Court