Mark J. Leavy is Of Counsel with Marks, O’Neill, O’Brien, Doherty & Kelly. He is admitted to practice in New Jersey and Pennsylvania. Mark represents individuals in corporations of every size and practices in our Professional Liability and Employment Practice Groups.

Mark graduated from The University of Pennsylvania in 1995, with a bachelor’s degree in Diplomatic History. He attended Rutgers University School of Law (Camden), graduating in 2004. During law school as a 2L, he participated in the Willem C. Vis International Moot Arbitration, traveling to Vienna, Austria to compete against law schools from around the globe in a moot arbitration under the 1980 Vienna Convention on the International Sale of Goods (CISG); and, as a 3L, he served as a Teaching Assistant for Advanced Sales Law, mentoring the arbitration team. Mark also served on the Rutgers Law Journal as a staff writer in his 2L year and then as the Articles Editor in his 3L year. Mark also authored the article “Discrediting Human Rights Abuses As An ‘Act of State’: A Case Study of the Repression of the Falun Gong in China and Commentary on International Human Rights Law in U.S. Courts,” 35 Rutg. L. J. 749 (2004). During law school, Mark interned at the New Jersey Office of the Attorney General, Division of Consumer Affairs, in the Professional and Occupational Boards section. Additionally, Mark served as a judicial extern for the Honorable Anne E. Thompson, Senior Judge, United States District Court for the District of New Jersey.

Following law school, Mark clerked for the Honorable William E. Nugent, J.S.C., of the Superior Court of New Jersey, Law Division, Atlantic County. During his clerkship, Mark also served as a Court trained Mediator, handling disputes in Special Civil Part matters.

Prior to joining Marks O’Neill, Mark was an attorney for several years at a prominent New Jersey law firm where he handled third-party insurance matters including auto, premises liability, property damage, and professional liability matters, and first-party insurance coverage disputes.

For nearly a decade, Mark was a Senior Associate in the Labor & Employment Group at a regional law firm based where he represented small and large corporations across various industries. He counseled companies in the full spectrum of labor and employment matters and handled extensive employment litigation, defending against claims of discrimination, harassment, wrongful termination, whistleblowing, retaliation, alleged violations of wage and hour laws, collective actions under the FLSA, as well as disputes relating to non-competition and non-solicitation agreements. 

Mark also handles a variety of complex commercial litigation matters, and his practice includes class action litigation defending against claims under consumer fraud laws, as well as FDCPA and TCPA claims.

Outside of work, Mark enjoys tennis, traveling, and reading historical non-fiction and biographies.

Mark J. Leavy
Of Counsel

Phone 856-406-1317

Mark J. Leavy PDF


  • J.D., Rutgers University School of Law (Camden), cum laude, 2004
  • B.A., The University of Pennsylvania, 1995

Bar Admissions

  • New Jersey
  • Pennsylvania
  • U.S. District Court for the District New Jersey
  • U.S. District Court for the Eastern District of Pennsylvania
  • U.S. Court of Appeals for the Third Circuit

Bar Associations

Practice Areas

  • Employment Law, Municipal & Public Entity
  • Professional Liability

Representative Cases