persons. Thus, we have held that collateral attacks against the legitimacy and filiation of children, [38] adoption,[39] and the validity of marriages (except void marriages)[40] are not allowed. Zamoranos' civil status as "divorced" belongs to the same category, and Pacasum cannot impugn it in an administrative case filed with the CSC, where the sole purpose of the proceedings is to determine the administrative liability, if any, of Zamoranos. III Finally, we have already passed upon the same Decree of Divorce in the earlier consolidated cases also involving Pacasum and Zamoranos. In Zamoranos v. People,[41] which involved a criminal charge for bigamy filed by Pacasum against Zamoranos based on her earlier marriage to De Guzman, we granted Zamoranos' motion to quash the criminal information for bigamy. We held that, based on the case records, "[i]t stands to reason therefore that Zamoranos' divorce from De Guzman, as confirmed by an Ustadz and Judge Jainul of the [Shari'a] Circuit Court, and attested to by Judge Usman, was valid, and, thus, entitled her to remarry Pacasum x x x." [42] Following the doctrine of conclusiveness of judgment, the parties are now bound by this earlier finding. In Tala Realty Services Corp., Inc. v. Banco Filipino Savings and Mortgage Bank,[43] we explained the doctrine of conclusiveness of judgment, otherwise known as "preclusion of issues" or "collateral estoppel": Conclusiveness of judgment is a species of res judicata and it applies where there is identity of parties in the first and second cases, but there is no identity of causes of action. Any right, fact, or matter in issue directly adjudicated or necessarily involved in the determination of an action before a competent court in which judgment is rendered on the merits is conclusively settled by the judgment therein, and cannot again be litigated between the parties and their privies whether or not the claim, demand, purpose, or subject matter of the two actions is the same. Thus, if a particular point or question is in issue in the second action, and the judgment will depend on the determination of that particular point or question, a former judgment between the same parties or their privies will be final and conclusive in the second if that same point or question was in issue and adjudicated in the first suit. Identity of cause of action is not required but merely identity of issue. In this case, the rule on conclusiveness of judgment is squarely applicable because Banco Filipino's action for reconveyance is solely based on a trust agreement which, it cannot be overemphasized, has long been declared void in a previous action that involved both Tala Realty and Banco Filipino, i.e., G.R. No. 137533. In other words, the question on the validity of the trust agreement has been finally and conclusively settled. Hence, this question cannot be raised again even in a different proceeding involving the same parties. Although the action instituted in this case is one for reconveyance, which is technically different from the ejectment suit originally instituted by Tala Realty in G.R. No. 137533, "the concept of conclusiveness of judgment still applies because under this principle, the identity of causes of action is not required but merely identity of issues. Simply put, conclusiveness of judgment bars the relitigation of particular facts or issues in another litigation between the same parties on a different claim or cause of action."[44] (Emphasis supplied; citations omitted.) Here, Pacasum's administrative complaint is wholly dependent on the continuing validity of the marriage between Zamoranos and De Guzman. However, we have already recognized that this marriage was dissolved in accordance with the Muslim Code in the case of Zamoranos v. People, which also involved the herein parties. Following the doctrine of conclusiveness of judgment, the parties are already bound by our previous ruling on that specific issue, that is, Zamoranos' divorce from De Guzman was valid which enabled her to contract the subsequent marriage with Pacasum. As a result, Pacasum's complaint for immorality based on Zamoranos' alleged bigamy has no leg to stand on. WHEREFORE, the petition is DENIED. The Amended Decision dated August 31, 2010 of the Court of Appeals in CAG.R. SP No. 01945-MIN is AFFIRMED. SO ORDERED. Sereno, C. J., no part. Carpio, Velasco, Jr., Leonardo-De Castro, Peralta, Bersamin, Del Castillo, Mendoza, Reyes, Perlas-Bernabe, Leonen, Caguioa, Martires, and Tijam, JJ., concur.