In Memoriam: Peter Dirk Siemsen (1929–2026)

Peter Dirk Siemsen, 1929-2026

We are saddened to announce the passing of Peter Dirk Siemsen on March 22, 2026, a well-respected and influential figures in the field of intellectual property (IP) in Brazil and internationally.

His career, spanning more than seven decades, was marked by an unwavering commitment to the development, strengthening, and internationalization of IP systems in Brazil and globally.

Mr. Siemsen was born in Rio de Janeiro, earned his degree from the State University of Rio de Janeiro, and was admitted to the Brazilian Bar Association (OAB) in 1955.

He was actively engaged with leading international organizations, including INTA, where he was a long-standing member, served on the Board, and was a recipient of the President’s Award. He was also a member the International Federation of Intellectual Property Attorneys (FICPI), the American Intellectual Property Law Association (AIPLA), the European Communities Trade Mark Association (ECTA), Marques, the Licensing Executives Society (LES), and the International Association for the Advancement of Teaching and Research of Intellectual Property (ATRIP). His contributions were widely recognized, including his induction into the IP Hall of Fame in 2013.

A founding partner of Dannemann Siemsen and a founding figure of the Brazilian Intellectual Property Association (ABPI) and the Inter‑American Association of Intellectual Property (ASIPI), where he served as Honorary President, Mr. Siemsen played a central role in positioning Brazil within the global IP community. He also served as president of the International Association for the Protection of Intellectual Property (AIPPI) and held leadership roles within the International Chamber of Commerce, in addition to acting as an arbitrator at the World Intellectual Property Organization (WIPO) Arbitration and Mediation Center and at the Court of Arbitration for Sport.

He authored a series of articles on industrial property and technology transfer in Brazil, Germany, Great Britain, Hungary, Japan, Spain, Switzerland, and the United States, and delivered lectures in Australia, Brazil, Europe, Japan, Latin America, South Africa, and the United States.

Beyond his remarkable professional achievements, Mr. Siemsen will be remembered for his generosity of spirit and his exceptional ability to bring people together. He was a mentor to many and a true builder of communities, fostering connections across countries, institutions, and generations.

In sport, he was a prominent figure in sailing, both as a competitor and in institutional roles. He won major titles, including the 1966 South American Championship in the International Star Class.

He also held leadership roles on the international stage, having served as president of the International Star Class Yacht Racing Association (ISCYRA), vice-president of the International Yacht Racing Union (IYRU)—now World Sailing—and general referee of the America’s Cup. He was also an international and Olympic judge, and a member of the Court of Arbitration for Sport (CAS). In 2010, he received the Beppe Croce Trophy, World Sailing’s highest honor, awarded for his exceptional contribution to the sport of sailing.

He is survived by his four children, to whom he was deeply devoted, including Peter Eduardo Siemsen and Elisabeth Siemsen, partners at Dannemann Siemsen, who honor and carry forward his remarkable legacy.

His impact is felt not only through the institutions he helped shape, but also through the many professionals and communities he inspired—a legacy that will undoubtedly endure.

His passing represents a profound loss to the global IP community.

Although every effort has been made to verify the accuracy of this article, readers are urged to check independently on matters of specific concern or interest.

© 2026 International Trademark Association