David Marion concentrates his practice on complex business litigation, antitrust and securities class actions, legal malpractice defense, first amendment/communications law and alternate dispute resolution. He acts as both plaintiffs and defense counsel in such litigation. 

David has achieved numerous noteworthy court victories, including seven-figure jury verdicts in an unfair competition case against a major broadcast network, and in a vertical price-fixing case; defense of a major public utility in a precedent-setting federal ERISA class action; and victories in the U.S. Supreme Court and numerous state and federal appellate courts. He was appointed by the U.S. District Court as Receiver on motion of the Securities and Exchange Commission in an action involving a Ponzi scheme, and as special master in complex federal multi-district litigations. 

Recognition and Involvement

Recognition & Involvement

David was elected Chancellor of the Philadelphia Bar Association and is former President of the Philadelphia Lawyers Club. He is the National Chancellor of the Tau Epsilon Rho Law Society. He was elected as a Fellowship in the American College of Trial Lawyers, the International Academy of Trial Lawyers and the American Academy of Appellate Lawyers, and has held leadership positions in a number of non-profit organizations.  

David received the James Wilson Award for service to the profession, school and community, the highest honor Penn Law School extends to a an alumnus, and was the recipient of the Judge Learned Hand Award from the American Jewish Committee. He has been listed in Chambers USA as a leading lawyer in commercial litigation since the honor's inception in 2003 and is described as a "very highly regarded trial attorney." Since 2004, in surveys of his peers, David has been selected as a Pennsylvania "Super Lawyer." He is uniquely listed by Best Lawyers in America® in six categories of law practice: Appellate Practice, Bet-the-Company Litigation, Commercial Litigation, First Amendment Law, Legal Malpractice Law, and Media Law. David was recognized by Best Lawyers as the 2019 Legal Malpractice Law "Lawyer of the Year" in Philadelphia. He was also named one of The Philadelphia Inquirer's "Influencers of Law" for Litigation and Dispute Resolution. David is currently serving as General Counsel to Encore Series Inc./the Philly Pops Orchestra.


Bar and Court Admissions



University of Pennsylvania Law School, JD, magna cum laude

University of Pennsylvania, Wharton School, BS in Economics

News & Insights


Anti-Defamation League, Board of Directors

Congregation Beth Sholom, Board of Directors

Federation of Jewish Agencies, Board of Directors

Philadelphia Bar Association

Rotary Club of Philadelphia

University of Pennsylvania Law Alumni Society


  • Serving as Special Master appointed by EDPA Judge Cynthia Rufe in the Generic Pharmaceuticals Price-Fixing Antitrust Cases
  • Serving as Court Appointed Receiver on motion of the U.S Securities and Exchange Commission in a Ponzi Scheme case where 92% of the victims' principal losses has been refunded to them to date
  • Successfully argued in the United States Supreme Court in a case establishing plaintiffs' burden to prove falsity in First Amendment libel cases
  • Successful appeals before the Pennsylvania Supreme Court, including a case liberalizing grant of summary judgment for defendants
  • Successfully achieved affirmance by the Second Circuit United States Court of Appeals of the grant of summary judgment against a group of New York City craft labor unions 
  • Successfully represented a client before the Third Circuit United States Court of Appeals in a precedent-setting ERISA case
  • Secured the affirmance of a seven-figure unfair competition verdict before the Third Circuit United States Court of Appeals
  • Secured a seven-figure jury verdict before the United States District Court of the Eastern District of Pennsylvania against a munitions manufacturing company
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