Legal Question in Criminal Law in California

If your roommate is on probation and has a search waiver, the police or probation can search his person and any residence or vehicle under his control. They are supposed to be limited to the areas that are either exclusively your roommate's or common areas. To protect yourself, you could install a lock on your door to designate it as yours alone. Areas that your roommate has access to, however are fair game, so they can search the living room, garage, etc.