Keith J. Mendelson

David W. Bowker is the partner-in-charge of the firm’s Washington DC office and chair of the International Litigation practice. He is a nationally renowned litigator with nearly 25 years’ experience representing corporate clients, nonprofits, museums, universities, individuals, international organizations, governments, and government officials in a wide range of high-stakes commercial and governmental disputes before the US Supreme Court, US Courts of Appeals, US District Courts, ...

William J. Cople III defends government contractors and commercial companies in a range of critical industries in government investigations, litigation, trials, and prosecutions involving the False Claims Act, Anti-Kickback statute, and Foreign Corrupt Practices Act, and handles corporate internal investigations, whistleblower claims, and Congressional investigations. He represents pharmaceutical, medical device, financial institution, and engineering and construction firms as trial counsel i...

Jason Chipman is widely recognized as a national leader in handling complex regulatory matters associated with data security, cyber incident response, the Committee on Foreign Investment in the United States (CFIUS) and related export controls.

David is the managing partner of the Washington, D.C. office, as well as the co-leader of the Investment Management Group. Prior to joining Sullivan & Worcester, David was Special Counsel in the Washington, D.C. office of Gibson, Dunn & Crutcher. He previously served as Assistant General Counsel for Legislation and Investment Company and Adviser Regulation at the Securities and Exchange Commission and as Counsel to SEC Commissioner Aulana Peters.

Robert W. Zelnick is a nationally recognized intellectual property (IP) lawyer with an established record of success. Although he is also a registered patent attorney, for more than two decades Robert has focused his practice on trademark, unfair competition and false advertising matters, where he counsels clients on complex IP issues and serves as lead counsel for major clients in federal trial and appellate courts. According to client feedback in World Trademark Review, as the former head o...

Marna S. Tucker has practiced law in the domestic relations field for almost forty years, and is a nationwide expert in complex divorces, domestic violence and prenuptial matters. She has been recognized several times as one of the "Top Divorce Lawyers" by the Washingtonian Magazine as well as one of the "Top Lawyers" in Washington, D.C. She was noted as one of the top divorce lawyers in the nation by Town and Country magazine. She is a Fellow of the prestigious American College of Trial Lawy...

Mimi Y. Liu is a top attorney recognized by Best Lawyers in the practice area(s) of Personal Injury Litigation - Plaintiffs. Mimi Y., who practices law in Washington, District of Columbia, has been recognized since 2025. This recognition is based on an exhaustive peer-review survey, reflecting the high esteem in which Mimi Y. is held by other top lawyers in the same geographic and legal practice area.

FOUNDING PARTNER For four years in a row from 2022-2025, Superlawyers magazine voted Mr. Jezic as one the Top 10 Best Lawyers in all of Maryland (among 40,000 lawyers). Mr. Jezic’s primary focus is winning - a Not Guilty verdict or a dismissal. Otherwise, his goal is to get a result beyond expectations. To this end, Mr. Jezic has built an astonishing record of success in winning jury trials for his clients: 88% of all his jury trials as a defense attorney have resulted in some type of w...

John B. Watkins is a top attorney recognized by Best Lawyers in the practice area(s) of Corporate Law and Mergers and Acquisitions Law. John B., who practices law in Washington, District of Columbia, has been recognized since 2005. This recognition is based on an exhaustive peer-review survey, reflecting the high esteem in which John B. is held by other top lawyers in the same geographic and legal practice area.

Michael L. Vogelsang, Jr., is a principal at The Employment Law Group ® law firm, where he frequently handles cases that involve whistleblower retaliation, employment discrimination, wrongful termination, and other workplace claims. Since joining the firm in 2007, Mr. Vogelsang has gained extensive experience representing federal employees. He specializes in navigating the administrative labyrinth of cases across dozens of departments and agencies, such as: the Department of Defense, the ...