Judicial compromise's res judicata effect
A judicial compromise has the effect of res judicata and is immediately executory and not appealable. The ultimate test in ascertaining the identity of causes of action -- whether or not the same evidence fully supports and establishes both the present cause of action and the former cause of action. Only substantial, and not absolute, identity of parties is required for res judicata.
According to the legal provision cited above (Art. 1809, Civil Code), a compromise may either be judicial or extra-judicial, depending upon whether its purpose be to terminate a suit already instituted or to avoid the provocation thereof. In the former case the compromise is deemed judicial while in the latter extra-judicial.
Whether it be judicial or extra-judicial, a compromise has, with respect to the parties the same authority as res judicata with the sole difference that only a compromise made in court may be enforced by execution, in accordance with the provisions of article 1816 of the Civil Code. Although a judicial compromise has the authority of res judicata as if a final judgment had been rendered therein, and maybe executed in the manner provided for by the Code of Civil Procedure, if the parties submit it for the consideration and approval of the court praying that the suit be considered terminated and the thing agreed upon be made effective (Manila Railroad Co. vs. Arzadon, 20 Phil., 452; Hernandez vs. Barcelon, 23 Phil., 599, 610; Decision of the Supreme Court of Spain of April 22, 1911), the judgment rendered to that effect shall be subject to the provisions of said Code of Civil Procedure, except that, as a judgment by consent, it may not be amended, modified nor corrected in any of its essential parts without a consent of all the parties to the compromise, on the ground that if the court changes it wholly or in part without such consent, it ceases to be a judgment agreed upon by them. Such exercise of judicial power would be tantamount to depriving the aggrieved party of his right to be heard in the manner provided for by law. (3 Freeman on Judgments, p. 2776 sec. 1352; 34 Corpus Juris, p. 2776, sec. 1352; 34 Corpus Juris, p. 418, sec. 668.) Neither can such judgment be reopened or set aside without the consent of the parties who applied for it to sanction and approve their compromise, converting said compromise into a judgment to terminate the suit, or without sufficient evidence that the compromise was obtained through error, deceit, violence, or forgery of documents, which are the only grounds authorized by article 1817 of the Civil Code on which to base on an action for the nullity of a judicial or extra-judicial compromise already perfected. (See Freeman on Judgments, Vol. 3, p. 2776, sec. 1352; 34 Corpus Juris, p. 419, sec. 670.) Yboleon vs. Sison, 59 Phil., 281, 290, 291. (G.R. No. L-4358)