Joseph O’Neill is a Senior Partner with Marks, O’Neill, O’Brien, Doherty & Kelly. He is admitted to practice in Pennsylvania and is a member of Pennsylvania, Philadelphia and the American Bar Associations.

Joseph graduated from Fordham University in 1977, summa cum laude, with a bachelor’s degree in philosophy. He then attended Temple University School of Law, graduating in 1980. During law school, he interned at the Philadelphia District Attorney’s office.

Joseph has lectured extensively on bad faith, as well as various toxic tort and environmental issues. Joseph has served as Chapter Counsel for Delaware Valley Chapter of the International Association of Special Investigation Unit (I.A.S.U.), an organization devoted to root out insurance fraud. He has lectured to the Pennsylvania Bar and regularly lectures on programs sponsored by the Insurance Society of Philadelphia. Joseph is a member of Claim and Litigation Management (CLM), Federation of Defense and Corporate Counsel (FDCC), and Professional Liability Underwriting Society (PLUS).

Since founding Marks O’Neill in 1986, Joseph has represented clients in defense litigation with particular emphasis on professional liability, employment litigation and environmental and toxic tort litigation. Joseph also defends municipalities, school districts and public officials in civil rights and other federal question cases and regularly consults on coverage, bad faith and motor vehicle litigation issues.

Joseph enjoys exercising, reading, going to the theater, watching sports, listening to music and looking at art.

Joseph M. O'Neill

Phone 215-832-4208

Joseph M. O'Neill PDF


  • J.D., Temple University School of Law, 1980
  • B.S., Fordham University, summa cum laude, 1977

Bar Admissions

  • Pennsylvania, 1980
  • U.S. District Court for the Eastern District of Pennsylvania, 1981
  • U.S. Court of Appeals for the Third Circuit, 1981

Bar Associations

  • American Bar Association
  • Pennsylvania Bar Association
  • Philadelphia Bar Association

Practice Areas

  • Construction Accident/Construction Defect
  • Professional Liability
  • Toxic Tort, Mass Tort, Environmental and Products Liability

Representative Cases