Does California have any law(s) permitting or restricting non-compete and/or non-solicitation clauses in an employment or independent contractor agreement?

Such clauses are designed to restrict a physician's ability to practice medicine in competition with the former employer/principal, and to prohibit the active solicitation of patients or clients, after the termination of the agency relationship.

If possible could you provide me a link to the law and summarize the key elements of the law?