Section 1094.5, subdivision (a) provides that: "Where the writ is issued for the purpose of inquiring into the validity of any final administrative order or decision made as the result of a proceeding in which by law a hearing is required to be given, evidence is required to be taken, and discretion in the determination of facts is vested in the inferior tribunal, corporation, board, or officer, the case shall be heard by the court sitting without a jury." Section 1094.6, subdivision (b) provides that judicial review may be had if a petition is filed not later than the 90th day following the date on which the decision becomes final, and the decision is final upon the expiration of the period during which reconsideration can be sought. Thus, section 1094.5 requires that a petitioner must file a writ of administrative mandate to exhaust judicial remedies prior to seeking a judicial forum in cases where a hearing is required to be given and evidence is required to be taken. (Keeler v. Superior Court (1956) 46 Cal. 2d 596, 297 P.2d 967 [where neither statute nor state personnel board's rules required a hearing, the scope of administrative review is not governed by section 1094.5].) Where a party fails to challenge a quasi-judicial decision by an administrative tribunal by administrative mandamus pursuant to section 1094.5, that failure gives collateral estoppel effect to the administrative agency's decision. ( McDaniel v. Board of Education (1996) 44 Cal. App. 4th 1618, 1621.) In other words, the administrative decision has "'achieved finality due to the aggrieved party's failure to pursue the exclusive judicial remedy for reviewing administrative action.'" (Ibid.) Section 1094.5, however, is not applicable in all situations involving administrative hearings. Case law holds that if an agency has discretion to grant a hearing and due process does not require a hearing, section 1094.5 does not apply even if a hearing is granted. ( Weary v. Civil Serv. Com. (1983) 140 Cal. App. 3d 189, 195, 189 Cal. Rptr. 442.)