Judge Illston was appointed to the U.S. District Court for the Northern District of California in May, 1995, and before then she was a partner in the law firm of Cotchett Illston & Pitre, in Burlingame, CA, specializing in civil litigation practice, with an emphasis on commercial litigation. Judge Illston is a member of various professional organizations, including the American College of Trial Lawyers and the American Board of Trial Advocates.

Susan Illston is on the Advisory Board for The Sedona Conference.