Lewis R. Clayton concentrates on intellectual property litigation and counseling at Paul, Weiss, Rifkind, Wharton & Garrison LLP, where he has been a partner since 1986. He has been chair and co-chair of the Committee on Intellectual Property of the Commercial and Federal Litigation Section of the New York State Bar Association and is co-chair of the Paul, Weiss Intellectual Property Litigation Group. He writes regular columns on intellectual property litigation for the New York Law Journal and the National Law Journal.

He has handled major litigations and counseled clients in a broad range of patent, copyright, trademark and unfair competition matters. He has handled major patent litigations, both as plaintiff and defendant, concerning patents in the cosmetics, computer and medical devices industries (among others), including successful enforcement of Revlon's patent on its revolutionary ColorStay lipstick. He has represented Castrol, Inc., a major marketer of motor oil, in five advertising litigations, winning federal court injunctions against the continued broadcast of competitors' nationwide advertising campaigns. He has handled major trademark litigations for Unilever, Revlon and other significant trademark holders. In 2001, he successfully represented Unilever in a groundbreaking trade secret dispute with Procter & Gamble. He recently represented CBS in copyright litigation concerning CBS's reality television program "Survivor".