The principle of res judicata applies to claims identical to those previously adjudicated, barring new actions based on the same issues, ensuring finality in litigation.

Introduction

[1] We heard this appeal on 14 February 2022 with 10 questions of law (QOL) granted at the leave stage for our determination. The 10 QOLs concern mainly issues of unjust enrichment; res judicata; limitation; constructive/implied trust; estoppel; frustration; reciprocal promises; and appellate jurisdiction. The 10 QOLs read:

(i) Whether the test for unjust enrichment is "act or delivery of thing that can be said to have done by the Plaintiffs which was not intended to be done gratuitously that had benefitted the defendants?

(ii) Whether res judicata applies to a 2nd action filed after the Federal Court in a 1st action has ruled it to be premature with unsatisfiled conditions precedent?

(iii) Whether the time ceases to run under the Sabah Limitation Ordinance ("SLO") during the duration of prosecution and appeal of a 1st action subsequently ruled by the Federal Court as premature and such time is excluded for filing a 2nd action?

(iv) Whether an admission of debt found and not extinguished can be categorised under constructive or implied trust thereby excluded under s 9 of SLO?

(v) Whether estoppel per se applies to admitted debt by a party from reneging its obligation to pay the admitted debt?

(vi) Whether a claim for unjust enrichment and/or for frustration falls under item 97 or 102 of SLO? If so, whether the limitation for unjust enrichment and/or frustration is 6 years or 12 years?

(vii) Whether a 2nd Panel of Court of Appeal may revisit and revise a finding by the 1st Panel of Court of Appeal on a same point of law and or fact? If so, what are the conditions under which a 2nd Panel of Court of Appeal may do so?

(viii) When does the cause of action arise and limitation starts to run for an admitted debt found to be not extinguished?

(ix) Whether the findings and pleadings in earlier judgments in a 1st action in respect of the same case by the High Court and Federal Court are binding on a 2nd Panel? If so, what are the circumstances in which the Court may go beyond the pleaded case and refer to an earlier judgment on the same case?

(x) Whether the test is "objective aim" or "real nature of transaction" to determine the order of performance of reciprocal promises?

[2] Before us, the major attack of the Court of Appeal decision was in respect of the alleged reopening of the issues that were already decided in the 1st 1997 suit in the sense that the Court of Appeal had redefined the meaning of "premature" inconsistent with what was held and decided by the Courts in the 1997 suit. This was raised in relation to the res judicata issue.

[3] Other matters concern the defence of limitation to the admitted debt that was allegedly not extinguished, unjust enrichment, constructive trust, frustration, estoppel and reciprocal promises. Our Decision

[4] Having read the cause papers and parties' written submissions and having heard and considered the oral submissions by both the learned Counsel on all issues raised, we were unanimous in our view that the one issue that will determine and dispose of the appeal was whether the Appellants' case was caught by res judicata.

[5] In that regard, we were with the learned Counsel for the Respondents that the Court of Appeal justices were correct in app