Cal. Bus. & Prof. Code § 450.5

A public member, or a lay member, at any time within five years immediately preceding his or her appointment, shall not have been engaged in pursuits which lie within the field of the industry or profession, or have provided representation to the industry or profession, regulated by the board of which he or she is a member, nor shall he or she engage in those pursuits or provide that representation during his or her term of office.