Mannion Prior

James F. Mannion

James F. Mannion

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Managing Partner

(610) 265-7800

Mannion Prior founder and Managing Partner James F. Mannion concentrates his practice exclusively on Orphans’ Court litigation, and is recognized as a leading member of Pennsylvania’s Orphans’ Court Bar. His practice includes fiduciary litigation, will contests, trust disputes, estate litigation, guardianship proceedings and litigation, fee and commission disputes, and non-profit/charitable litigation.

James has successfully litigated at the trial and appellate court levels. He has served as lead counsel on numerous cases of first impression, including the first reported decision recognizing a claim for tortious interference with an inheritance under Pennsylvania law, and the 2005 Pennsylvania Superior Court en banc decision in W.W. Smith Trust.

James’ many publications include The Presumption of Undue Influence and the Shifting Burden of Proof, cited and relied upon by judges throughout Pennsylvania.

He lectures frequently on fiduciary litigation and Orphans’ Court matters, and has served as an expert witness in fiduciary litigation matters.


  • B.B.A. 1987, Pace University

  • J.D. 1990, The George Washington University National Law Center

  • L.L.M. in Taxation 1993, Villanova University School of Law

Bar Admissions

  • Admitted to practice in Pennsylvania

  • Admitted to practice in the United States Tax Court


  • Best Lawyers in America, “Lawyer of the Year” – 2018

  • The Best Lawyers in America ©, Litigation – 2011-2019

  • American Lawyer Media and Philadelphia Magazine, Pennsylvania “Super Lawyer” – 2004-2018

  • The Best Lawyers in America ©, Trusts & Estates – 2003-2010

  • AV® Preeminent™ Peer Review Rated by Martindale-Hubbell


  • Court of Common Pleas of Montgomery County, Civil Trial Division, Discovery Master

  • The American College of Trust and Estate Counsel (ACTEC), Fellow

  • ACTEC Fiduciary Litigation Committee and Attorney Malpractice Subcommittee, Member

  • Pennsylvania Joint State Government Commission Advisory Committee on Decendent’s Estate Laws, Member

  • Joint State Subcommittee on Orphans’ Court Matters, Member

  • Pennsylvania Supreme Court Orphans’ Court Procedural Rules Committee, Deputy Counsel 2006-2008

  • Pennsylvania Bar Association, Member

  • Philadelphia Bar Association, Probate and Trust Law Section

  • Montgomery County Bar Association, Director

  • Montgomery County Bar Association, Rules of Orphans’ Court Committee, Co-Chair

  • Montgomery County Bar Association, Bench Bar Executive Committee, Member

Previous Experience

  • Smith, Aker, Grossman & Hollinger

  • Ballard Spahr Andrews & Ingersoll, LLP

  • Dilworth Paxon Kalish & Kauffman (Now Dilworth Paxson, LLP)