Requa

Appellants Joe Requa, Wendell G. Moen, Jay Davis, and Donna Ventura (hereafter collectively Retirees) all spent decades working at *216 the Lawrence Livermore National Laboratory (Livermore). During their employment there, Livermore was operated by the University of California (the University or UC), a state agency governed by The Regents of the University of California (the Regents). After retiring from Livermore, Retirees all received University-sponsored group health insurance benefits.

In 2007, management and operation of Livermore was transferred from the University to a private consortium. On January 1, 2008, Retirees’ University-sponsored group health insurance was terminated, and the consortium assumed responsibility for providing Retirees’ health insurance benefits.

Retirees later brought an action for mandamus against the Regents, claiming that the elimination of their University-sponsored group health insurance benefits constituted an unconstitutional impairment of either an express or implied contract the Regents had formed with Retirees. Their petition also claimed the doctrines of promissory and equitable estoppel prohibited the termination of their…