Effects of res judicata = law of the case, bar to relitigation

It cannot be validly asserted by respondents in their comment that the Court never had the opportunity to pass upon the issues of xxx the illegality of the summary dismissal of the petitioner, and xxx did not even address itself to the issues and squarely pass upon the same. The Resolution dated 18 May 1987 did resolve the issues raised in the pleadings, except with respect to the constitutionality of Section 40 of P.D. 807. Consequently, upon attaining finality on 8 June 1987, the resolution became the law of the case and constituted a bar to any relitigation of the same issues in any other proceeding under the principle of res judicata. In fine, our 18 May 1987 Resolution was a final judgment on the merits. Respondents cannot be allowed now to invoke the summary dismissal of petitioner on 2 January 1986 as justification for his second dismissal on 8 February 1988. [G.R. No. 107841. November 14, 1996]