Mr. McMahon worked as a chemical engineer for Proctor and Gamble for seven years, prior to entering patent law practice. In 1976, while in law school, he joined the law firm of Fishburn, Gold and Litman, which was established in 1843. He became managing partner of the firm in 1982. In 2000, he formed a separate firm. Mr. McMahon’s practice is mainly in the preparation and prosecution of patents and trademarks, but also is involved in other intellectual property matters.