Res judicata also known as “Claim Preclusion”. It is a Latin term for “a matter already Judged.” It simply means that one cannot agitate a matter in a Court of law on which a Judgment has already been delivered.
In British India the rule of Res Judicata was first introduced by Section 16 of the Bengal Regulation, III of 1973 which prohibited the Zilla and City Courts from entertaining any cause which, from the production of a former decree or the record of the Court, appears to have been heard and determined by any Judge or any Superintendent of a Court having competent jurisdiction.
The doctrine of res judicata rests on the principle that one should not be vexed twice for the same cause and there should be finality to litigation. It also rests on public policy. The basic principle of the doctrine of res judicata is that cause of action for the second suit or action being merged in the judgment of the first, does not survive any more. It is, however, necessary that in order to operate as estoppel, the decision in the first suit must have been given by a Court or the Tribunal having jurisdiction. If the first decision is non est, the plea of res judicata cannot be founded [Sayyed Ali v. Andhra Pradesh Wakf Board  2 SCC 642].
That principle of finality of litigation is based on high principle of public policy. In the absence of such a principle great oppression might result under the colour and pretence of law in as much as there will be no end of litigation and a rich and malicious litigant will succeed in infinitely vexing his opponent by repetitive suits and actions. This may compel the weaker party to relinquish his right. The doctrine of Res Judicata has been evolved to prevent such an anarchy. That is why it is perceived that the plea of Res Judicata is not a technical doctrine but a fundamental principle which sustains the Rule of Law in ensuring finality in litigation. This principle seeks to promote honesty and a fair administration of justice and to prevent abuse in the matter of accessing Court for agitating on issues which have become final between the parties .
“But the question as to whether a citizen should be allowed to challenge the validity of the same order by successive petitions under Art. 226 cannot be answered merely in the light of the significance and importance of the citizens’ fundamental rights. The general principle underlying the doctrine of res judicata is ultimately based on considerations of public policy. One important consideration of public policy is that the decisions pronounced by courts of competent jurisdiction should be final, unless they are modified or reversed by appellate authorities; and the other principle is that no one should be made to face the same kind of litigation twice over, because such a process would be contrary to considerations of fair play and justice, vide : Daryao v. State of U.P., 1962-1 SCR 575; (AIR 1961 SC 1457).” (Devi Lal Modi v. STO AIR 1965 SC 1150)
Identity in respect of three matters for res judicata
Before the plea of res judicata is raised there shall have to be identity in respect of three matters, namely :
( i) subject matter,
(ii) cause of action and
(iii) persons and parties
Conditions for res judicata
In order to constitute a matter asres judicata, the following conditions must be satisfied :
(i)There must be two suits – one former suit and the other subsequent suit;
(ii)The Court which decided the former suit must be competent to try the subsequent suit;
(iii)The matter directly and substantially in issue must be the same either actually or constructively in both the suits;
(iv)The matter directly and substantially in issue in the subsequent suit must have been heard and finally decided by the court in former suit;
(v)The parties to the suits or the parties under whom they or any of them may claim must be the same in both the suits;
(vi)The parties in both the suits must have litigated under the same title