Mathieu J. Shapiro

Mathieu is the Managing Partner and General Counsel of Obermayer, as well as the Chair of the Appellate Department and Co-Chair of the Litigation Department.  His practice focuses on appellate and business litigation, guided by a disciplined, client-centered approach that begins with a clear understanding of the client’s objectives and measures success accordingly.

In his appellate practice, Mathieu has briefed and argued matters before all levels of Pennsylvania’s appellate courts and in multiple federal courts, including the United States Court of Appeals for the Second, Third, and Seventh Circuits.  Leveraging his appellate experience, Mathieu works closely with trial teams to frame issues clearly, develop durable records, and present arguments designed to withstand scrutiny at every stage.

In his business-litigation practice, Mathieu represents businesses and individuals in complex disputes involving shareholder conflicts, fiduciary-duty claims, and sophisticated commercial contracts.  His role as Managing Partner brings an added dimension to his client representation.  By helping lead and operate a professional services organization himself, he understands firsthand the operational, financial, and strategic considerations that inform business decision-making—experience that shapes his pragmatic advice on risk, cost, and outcomes in litigation.

Mathieu is also the co-author, with the Honorable Paul S. Diamond of the United States District Court for the Eastern District of Pennsylvania, of the Director & Officer Liability chapter in the ABA’s Business and Commercial Litigation in Federal Courts treatise, a leading resource on complex federal litigation.

Outside the office, Mathieu enjoys cooking, traveling, skiing, and spending time with his wife and children.  A devoted Philadelphia sports fan, he is always hopeful for another championship parade.

Mathieu brings an appellate lens to complex litigation, briefing, and arguing matters that shape outcomes at every stage of a case. His experience includes:

• Briefing and arguing appeals before all levels of Pennsylvania’s appellate courts and in multiple federal courts of appeals, including the Second, Third, and Seventh Circuits.
• Securing dispositive rulings and reversals in high-stakes matters involving constitutional questions, statutory interpretation, and municipal authority, including a Pennsylvania Supreme Court decision confirming a mayor’s authority to appoint members to a municipal body.
• Partnering with trial teams from the outset of litigation to frame issues, preserve error, and develop records designed to withstand appellate scrutiny.
• Representing municipalities, school districts, and other public entities in high-profile litigation, including precedent-setting matters before Pennsylvania appellate courts.
• Guiding closely held and family-owned businesses through “business divorce” disputes, achieving negotiated resolutions while protecting long-term enterprise value.
• Obtaining seven-figure recoveries for businesses harmed by professional negligence and accounting malpractice.
• Enforcing restrictive covenants and protecting trade secrets through injunctions and multi‑million-dollar settlements on behalf of employers.
• Defending companies in data-breach and privacy litigation, securing dismissals, summary judgment, and favorable resolutions of complex claims involving alleged failures to safeguard confidential information.
• Representing financial institutions and their customers in disputes involving alleged misconduct, investment losses, and contractual obligations, resulting in favorable judgments and significant settlements.
• Defending merger and acquisition transactions against shareholder challenges, obtaining dismissals, venue transfers, and summary judgment on fiduciary-duty and securities-law claims.
• Representing attorneys and law firms in sensitive matters before the Pennsylvania Disciplinary Board, including responding to DB-7 inquiries and defending against professional conduct allegations.
• Litigating complex commercial matters involving leases, franchise agreements, U.C.C. interests, zoning disputes, and business torts through trial, arbitration, and appeal.
• Handling class actions and multidistrict litigation, including matters involving insurance coverage, employment claims, and large-scale commercial disputes.

Across all matters, Mathieu approaches litigation with the end in mind-focusing on clarity of issues, disciplined strategy, and outcomes that will hold up on appeal.

Mathieu’s practice reflects a sustained focus on appellate advocacy and the role of appellate strategy in complex litigation, including issue framing, standards of review, and preserving arguments for appeal. As Managing Partner of Obermayer, he brings that same disciplined, big-picture perspective to the firm’s strategic direction and to the development of its litigation and appellate capabilities.

Mathieu is the co-author, with the Honorable Paul S. Diamond of the United States District Court for the Eastern District of Pennsylvania, of the “Director & Officer Liability” chapter in the ABA Section of Litigation treatise Business and Commercial Litigation in Federal Courts (Thomson/West), a leading national resource on complex federal litigation.

Mathieu has been recognized by his peers for his work in commercial litigation, including selection to The Best Lawyers in America® (2024–2026) and Pennsylvania Super Lawyers® (2022–2025).

He was also recognized as a finalist in The Legal Intelligencer’s 2025 Pennsylvania Legal Awards for the Best Law Firm Mentors award, reflecting his commitment to developing the next generation of litigators and appellate advocates.

Awards Won*

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