(a) Except as provided in subdivision (b), if a person who is retired for service or disability under this system is appointed or elected to serve as a judge, he or she shall reinstate from retirement and again become a member of the system pursuant to this chapter.
(b) This section shall not apply to a retired judge who is assigned to serve in a court pursuant to Section 68543.5, and he or she shall not earn service credit or be entitled to retirement benefits under this part for that service.