Stephen is Co-Chair of Heller Ehrman's Antitrust and Trade Regulation National Practice Group. His practice combines substantial work in antitrust and other complex civil litigation, and he is currently co-lead counsel to Microsoft Corporation in numerous cases filed in California on behalf of indirect purchasers of the company's software and counsel to VISA U.S.A. in separate lawsuits brought by the U.S. Dept. of Justice and a nationwide class of retailers. Stephen has also argued over 50 federal and state appeals including several cases in the California and United States Supreme Courts.