Marc J. Sonnenfeld

Partner

Marc J. Sonnenfeld is a partner in Morgan Lewis's Litigation Practice and head of the Securities Litigation Group in Philadelphia. His practice focuses on defending securities and shareholder litigation and related regulatory and enforcement proceedings, defending shareholder class and derivative litigation challenging public company acquisitions, and counseling directors and officers and board committees on corporate governance issues. In addition, he has served as counsel for board of directors' special litigation committees for several public companies.

Mr. Sonnenfeld was recently named a 2013 Client Service All-Star by BTI Consulting Group and was one of five attorneys named Securities MVP by Law360 in 2012. In addition, Morgan Lewis's Securities Practice was named Law360 Securities Group of the Year. Noted by Chambers USA: America's Leading Lawyers for Business (2012) as a "a great securities and derivative suit litigator," Mr. Sonnenfeld has successfully defended shareholder class and derivative actions against public and private corporations, controlling shareholders, directors and officers, and underwriters arising under federal and state law.  

Mr. Sonnenfeld has led the teams defending putative securities class actions around the country, and has secured motions to dismiss in many of those cases. He has defended shareholder class actions in federal and state courts, challenging merger transactions valued, collectively, in excess of $10 billion. He has led teams representing the underwriter defendants in putative securities class actions, and AIG has approved Mr. Sonnenfeld on its panel for the defense of directors and officers in securities litigation.

Mr. Sonnenfeld's substantial trial and appellate experience includes two defense verdicts in the last five years-one representing a large developer before a jury in an action brought by a competitor alleging tortious interference with plans to develop a competing mall, and the other representing a software manufacturer in an action brought by a competitor alleging false advertising in violation of the Lanham Act.   In addition, one of Mr. Sonnenfeld's trials was the subject of a trial practice book, Herbert J. Stern and Stephen A. Saltzburg, Trying Cases to Win: Anatomy of a Trial (Aspen 1999).

Mr. Sonnenfeld's appellate practice has included appearing as amicus curiae in several significant cases. For example, in Cuker v. Mikalauskas, 547 Pa. 600, 692 A.2d 1042 (1997), Mr. Sonnenfeld filed an amicus brief on behalf of the Pennsylvania Chamber of Business & Industry, the Greater Philadelphia Chamber of Commerce, and the Greater Pittsburgh Chamber of Commerce, successfully urging adoption of the American Law Institute's Principles of Corporate Governance provisions concerning termination of shareholder derivative litigation and articulation of the "business judgment rule." In two other amicus briefs on behalf of the Pennsylvania, Philadelphia, and Pittsburgh Chambers, Mr. Sonnenfeld successfully urged that the imposition of punitive damages under the facts of those cases was contrary to public policy.

Mr. Sonnenfeld is a fellow of the American College of Trial Lawyers and has been named one of Philadelphia's top business litigators in The Best Lawyers in America since 1997, most recently being selected as a "Securities Lawyer of the Year" (2013). He was selected by Philadelphia Magazine as one of the 100 "Pennsylvania Super Lawyers." Mr. Sonnenfeld was awarded the 2010 Wells Fargo Fidelity Award from the Philadelphia Bar Association for his work helping to develop and maintain the Commerce Court Program in the Philadelphia Court of Common Pleas.

Mr. Sonnenfeld was on the faculty for the Pennsylvania Bar Institute seminar on the fiduciary duties of directors in 2012, the Crittenden Insurance Forum in 2009, and the PLUS D&O Symposium in 2010. He has served as chair of the Philadelphia Bar Association's Board of Governors and co-chair of its Business Court Task Force.

Mr. Sonnenfeld is a 1968 graduate of Swarthmore College and a 1971 graduate of Harvard Law School. In 1972, he served as law clerk to Judge Joseph S. Lord, III, then Chief Judge of the U.S. District Court for the Eastern District of Pennsylvania. Mr. Sonnenfeld has served on the board of managers of Swarthmore College, where he has chaired the Audit Committee, and on the national board of trustees of the American Inns of Court Foundation.

Mr. Sonnenfeld is admitted to practice in Pennsylvania, the District of Columbia, Massachusetts, and Florida and before the U.S. Supreme Court.