LEGAL PRINCIPLE: CIVIL PROCEDURE — Res Judicata — Preconditions for Success
PRINCIPLE STATEMENT
For the plea of estoppel per rem judicatam to succeed, the party relying on it must establish that — (i) the parties or their privies are the same, that is to say, that the parties involved in both the previous and present proceedings are the same; (ii) the claim or the issue in dispute in both the previous and present actions are the same; (iii) the res, that is to say, the subject matter of the litigation in the two cases is the same; (iv) the decision relied upon to support the plea of estoppel per rem judicatam must be valid, subsisting and final and (v) the court that gave the previous decision relied upon to sustain the plea must be a court of competent jurisdiction.
RATIO DECIDENDI (SOURCE)
Per Iguh, JSC Oshodi v. Eyifunmi (2000) NLC-531995(SC) at pp. 20–21; Paras. D–A.
"For the plea of estoppel per rem judicatam to succeed, the party relying on it must establish that — (i) the parties or their privies are the same, that is to say, that the parties involved in both the previous and present proceedings are the same; (ii) the claim or the issue in dispute in both the previous and present actions are the same; (iii) the res, that is to say, the subject matter of the litigation in the two cases is the same; (iv) the decision relied upon to support the plea of estoppel per rem judicatam must be valid, subsisting and final and (v) the court that gave the previous decision relied upon to sustain the plea must be a court of competent jurisdiction."
EXPLANATION / SCOPE
Res judicata requires strict proof of five cumulative preconditions: (1) identity of parties or privies; (2) identity of claim or issue; (3) identity of subject matter (res); (4) a valid, subsisting, final decision; and (5) a court of competent jurisdiction. Failure to establish any one element defeats the plea. These requirements ensure the doctrine is applied only where true identity exists and where the prior adjudication was fully authoritative. The burden rests on the party asserting estoppel to prove all five elements. This rigorous framework balances finality against the right to be heard on genuinely new or different matters.