WILLIAM J. NISSEN is a partner of Sidley Austin LLP, in Chicago, Illinois, and has practiced with the firm since 1976. From 1982-1984 he was General Counsel of Heinold Commodities, Inc., a Chicago-based futures commission merchant. His law practice includes representing clients, including futures commission merchants and introducing brokers, institutional users of the futures markets, fund managers and exchange members in litigation and regulatory matters involving the futures and OTC derivatives markets. He has been named the Best Lawyers' 2013 Chicago, Derivatives and Futures law "Lawyer of the Year." Best Lawyers designates "Lawyers of the Year" in high-profile legal practice areas in large legal communities.