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Mannion Prior, LLP

United States 2025

Overview

Content is provided by the firm.
Mannion Prior, LLP was formed in August 2001. Before establishing the firm, James F. Mannion and Karl Prior, collectively, gained over 20 years experience at large, nationally-prominent law firms.

We are Pennsylvania’s premier fiduciary litigation boutique, focusing our practice primarily in the Orphans’ Court Division of the Court of Common Pleas. Our practice areas include will contests, trust and trustee litigation, fee and commission disputes, estate litigation, and guardianship and incapacity proceedings. We also represent clients in complex business disputes and commercial litigation matters in Pennsylvania and federal courts.

We emphasize tenacious, reasoned, and intellectual representation of every client in every matter. Toward this end, we have built our firm with attorneys qualified to serve your needs. We maintain the highest standards of professionalism in our work, and our client successes reflect that professionalism. Our firm has been involved in seminal fiduciary litigation decisions, and our attorneys frequently lecture and write on Orphans’ Court practice and procedure.

Rankings

Mannion Prior, LLP is metro ranked in 1 practice areas. Best Law Firms rankings are based on a rigorous evaluation process.

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Metro Rankings

Philadelphia
Tier 1 for Litigation - Trusts and Estates

Rankings

Regional Rankings

Philadelphia
Tier 1 for Litigation - Trusts and Estates

Practice Areas

The below are areas of legal specialty volunteered by the firm and do not designate a specialty in which a Best Law Firms ranking is held.
  • Trusts and Estates

Individuals Recognized in The Best Lawyers in America®

Mannion Prior, LLP has 5 lawyers recognized for individual performance in the 2025 edition of The Best Lawyers in America®. By receiving this Best Lawyers recognition from their peers for their professional excellence, these lawyers made Mannion Prior, LLP eligible for evaluation for Best Law Firms rankings. For almost two decades, Best Lawyers has awarded these singular accolades, making them the foundation of our Best Law Firms awards. Read more about our Best Lawyers process here.
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Main Location

King of Prussia, PA
840 First Avenue, Suite 100
King of Prussia, PA 19406-1459
United States
610-265-7800 Call our King of Prussia, PA location at 610-265-7800 Get Directions Get directions to our King of Prussia, PA location

Office Locations

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