In 2001, William Nassar opened his own practice in Century City, providing specialized services to large law firms serving high net-worth individual, along with medical device FDA work. In 2002, William merged his practice with another Redlands, California law firm to address the needs of the local Inland Empire community shortly after he left Bourns, Inc. after a two-year anti-trust trial that ended with a verdict in excess of $150 million.

In early 2006, William Nassar established the Law Offices of William M. Nassar & Associates, Inc. The firm serves clients in Redlands, Riverside, Ontario, Palm Springs, San Bernardino, Orange County and the greater Los Angeles area in matters of estate planning, probate, immigration, real estate, business formation, transactional business matters, civil and coporation litigation.

Prior to becoming an attorney, William M. Nassar worked in the private sector from 1989 to 2001, primarily with Bourns, Inc., a large multi-national privately-held company, with headquarters in Riverside, California.  His business responsibilities and travels afforded him the opportunity to gain extensive knowledge about and experience in business structures of small and large enterprises, as well as corporate governance, business litigation, estate planning and succession planning.