Mr. Sieff is a former Staff Assistant to the U. S. Congressional Office of Minority Leader; Law Intern to Justice Winslow Christian, California Court of Appeal; Staff Assistant, Department of Justice, San Francisco, California; and private corporate counsel and counselor at law in Los Angeles, California . Mr. Sieff became licensed as a Real Estate Broker in 1980.

Professional affiliations have included the Santa Monica Bar Association (Past President), San Fernando Valley Bar Association (Vice Chair of Small Firms section and member of Litigation and Business Law sections), State Bar of California (Litigation, Business Law, and Small Firm sections); and admission to practice before the U.S. Supreme Court, Court of Appeals (9th Circuit), U. S. District Court, U. S. Tax Court, and all courts of the State of California.

Community affiliations have included the Santa Monica Junior Chamber of Commerce (Past President), Santa Monica Chamber of Commerce (Past Director), Rotary Club of Santa Monica (Past Director), American Red Cross (Local Director), Boys and Girls Club (Council Member), and volunteer for several youth sports teams.