Sean is a Senior Partner with Marks, O’Neill, O’Brien, Doherty & Kelly, P.C. and the managing partner of the firm’s New Jersey office.  Sean also heads the Professional Liability practice group.

Prior to joining the firm, Sean tried numerous cases while serving as an assistant District Attorney in the City of Philadelphia under now Chief Justice Ronald Castille. In his over twenty-five years of experience at Marks, O’Neill, O’Brien, Doherty & Kelly, P.C., Sean has handled various types of professional liability litigation, including medical and legal malpractice claims and those against insurance, financial and real estate professionals. Sean has extensive experience in complex employment and D&O litigation including claims of discrimination, wrongful termination and executive malfeasance. His practice also includes a significant amount of class action litigation ranging from national medical billing litigation to FDCPA and TCPA claims.

In municipal and constitutional law practice, Sean defends school boards, law enforcement and public officials against claims of constitutional deprivation and allegations of excessive force. He has appeared before the United States Third Circuit Court of Appeals, the New Jersey Supreme Court and briefed such matters for the United States Supreme Court.

  • Cottrel v. Zagami, Inc., 215 N.J. 483, 2013; Perez v. Zagami, LLC, 213 N.J. 530, 2013;
  • (Established as a case of first impression that the New Jersey Civil Rights Act does not permit actions against private parties not acting under color of law.)
  • SG and AG vs. Sayreville Broad of Education, 333 F.3b 417(3rd cir) 2003; (Prevailed on constitutional challenge to zero tolerance school policies)
  • Crawford, et al v. Davy, et al, 2009 N.J. Super, Unpub. LEXIS 3226 (Dismissal of constitutional challenge to school program)
  • Agostino v. Credit Collection Services, 210 U.S. Dist. Lexis 135310 (Denial of FDCPA and RICO class certification)
  • Florence v. Board of Chosen Freeholders, 621 F.3d 296 (2010 U.S. App. Lexis 19548) (Amicus on precedential decision overturning prohibition of strip searches)
  • Goldsmith v. Camden County Surrogates Office, 408 N.J. Super. 376 (App. Div. 2009) cert. den. 205 N.J. 502. (Dismissal of class action filed under OPRA)

Sean X. Kelly
Partner / New Jersey

Phone 856-663-4300

Sean X. Kelly PDF


  • J.D., Villanova University, 1988
  • B.A., Albright College, 1985

Bar Admissions

  • New Jersey, 1988
  • Pennsylvania, 1988
  • U.S. Court of Appeals for the Third Circuit, 1989
  • U.S. Supreme Court, 2004

Bar Associations

  • New Jersey Bar Association
  • Pennsylvania Bar Association

Practice Areas

  • Employment Law, Municipal & Public Entity
  • Professional Liability


New Jersey
Cherry Tree Corporate Center, 535 Route 38 East, Suite 501, Cherry Hill, NJ 08002