California Code, Government Code - GOV § 11425.60

(a) A decision may not be expressly relied on as precedent unless it is designated as a precedent decision by the agency.

(b) An agency may designate as a precedent decision a decision or part of a decision that contains a significant legal or policy determination of general application that is likely to recur.  Designation of a decision or part of a decision as a precedent decision is not rulemaking and need not be done under Chapter 3.5 (commencing with Section 11340).  An agency's designation of a decision or part of a decision, or failure to designate a decision or part of a decision, as a precedent decision is not subject to judicial review.

(c) An agency shall maintain an index of significant legal and policy determinations made in precedent decisions.  The index shall be updated not less frequently than annually, unless no precedent decision has been designated since the last preceding update.  The index shall be made available to the public by subscription, and its availability shall be publicized annually in the California Regulatory Notice Register.

(d) This section applies to decisions issued on or after July 1, 1997.  Nothing in this section precludes an agency from designating and indexing as a precedent decision a decision issued before July 1, 1997.