John P. Sheridan

John P. Sheridan

New York, New York
(212) 425-3240
(212) 509-8942

John has over twenty years of experience representing labor unions and Taft-Hartley benefit funds in state and federal courts and before administrative agencies and arbitration tribunals in disputes related to the NLRA, the LMRDA, ERISA, union trusteeships, union discipline, contractual grievances, harassment and discrimination, retaliation, and alleged denial of benefits.  John represents his union clients in labor-related matters, including arbitration, the defense of unfair labor practice charges, and collective bargaining negotiations.  He also assists his union clients with compliance with the LMRDA. 

John assists his benefit fund clients with the development, administration, and governance of ERISA-qualified, multiemployer plans, including complying with ERISA’s fiduciary duty provisions and its reporting and disclosure requirements.  Before joining Marrinan & Mazzola Mardon, John worked in the labor and employment department in a large firm in New Jersey, and prior to that, he worked for a union-side law firm in Boston, Massachusetts.

Areas of Practice

  • Labor
  • Employment

Litigation Percentage

  • 70% of Practice Devoted to Litigation

Bar Admissions

  • Massachusetts, 1994
  • U.S. District Court District of Massachusetts, 1995
  • New Jersey, 1998
  • U.S. District Court District of New Jersey
  • New York, 2001
  • U.S. District Court Southern District of New York, 2002
  • U.S. District Court Eastern District of New York, 2003
  • U.S. Court of Appeals 1st Circuit
  • U.S. Court of Appeals 2nd Circuit
  • U.S. Court of Appeals 3rd Circuit
  • U.S. Court of Appeals 4th Circuit
  • U.S. Court of Appeals District of Columbia Circuit


  • Boston College Law School, Boston, Massachusetts - 1994
  • Harvard College
    • A.B. - 1990