Becker & Poliakoff

James J. Mahon



James J. Mahon LinkedIn link.




      • Fordham University School of Law, J.D.
      • College of the Holy Cross, B.A., History

    Bar Admissions

      • New York
      • New Jersey

    Court Admissions

      • New York State Courts
      • United States Court of Appeals for the Second Circuit
      • United States Court of Appeals for the Third Circuit
      • United States District Court for the Southern District of New York
      • United States District Court for the Eastern District of New York
      • United States District Court for the District of Vermont
      • United States Tax Court
      • United States Court of Claims


  • German
  • Spanish



Jim Mahon has more than 30 years of experience as a civil and criminal litigator in Federal and State courts. Jim concentrates his practice on criminal and civil tax controversies, white collar criminal matters, and civil litigation. He represents clients facing criminal charges in state and federal courts, individuals under government investigation, and taxpayers before the Internal Revenue Service and the NY State Department of Taxation.

Jim’s commercial litigation practice includes banking, ERISA benefits and contributions, and securities matters. He has successfully represented clients subject to claims involving professional malpractice, labor and employment disputes, tax shelters, property allocation, matrimonial disputes, probate disputes, and disputes arising out of the misappropriation of databases and trade secrets.

Mr. Mahon serves as a mediator to the Commercial Part of the New York State Supreme Court, New York County. His practice also includes federal and state taxpayer representation in criminal and civil cases, business fraud, and other white-collar defense work. He has represented clients before various state and federal agencies, including the Internal Revenue Service, the New York State Department of Taxation & Finance, the SEC, the NASD, the EEOC and the NLRB. Prior to entering the legal profession, Jim served in the United States Peace Corps in Panama.


  • As of 2023, Mr. Mahon is involved in two litigations concerning insurance coverage disputes in New Jersey and New York.
  • Litigated major coverage dispute involving disclaimer by insurance company of coverage for condominium’s water damage where insurance company conceded coverage after completion of discovery.
  • Defense of charitable foundation, Services for Hidden Intelligence (SHI), against criminal charges brought by the state of New Jersey. Charges included corruption of public resources, theft by unlawful taking or disposition, financial facilitation of criminal activity and misapplication of entrusted property stemming from SHI’s support of a non-sectarian school for children with profound disabilities. Represented client in two-year investigation and ensuing jury trial, which resulted in client’s acquittal of all charges. The Foundation has since been able to resume its charitable work in the Lakewood, NJ community.
  • In a case of first impression, successfully established that an online database owned by a financial planner employed by a major accounting firm could be the subject of a common-law conversion action. The matter was tried by a jury, and the plaintiff’s jury verdict was affirmed on appeal.
  • Successfully defended actions against 100+ makers of investment notes against major bank, and successfully participated in the prosecution of a class-action claim on behalf of these investors against that bank.
  • Successfully defended a Nurse Practitioner wrongly accused of enterprise corruption and obtained dismissal of all charges.
  • In a case of first impression, successfully litigated the limitations of stop orders under the uniform commercial code.
  • Successfully defended a taxpayer against a claim made by the United States that he personally was liable for more than $300,000 in employment taxes. The government conceded that he was not a responsible person as defined by the Internal Revenue Code.
  • Represented a financial planner who was indicted for filing a false statement with the NASD by not disclosing a previous conviction for insider trading. The matter was tried to verdict in the United States District Court for the southern district of New York, and resulted in a verdict of not guilty.