CPC Section 11

11. Res judicata.
No Court shall try suit or issue in which the matter directly and substantially in issue has been directly and substantially in issue in a former suit between the same parties, or between parties under whom they or any of them claim, litigating under the same title, in a Court competent to try such subsequent suit or the suit in which such issue has been subsequently raised, and has been heard and finally decided by such Court.

Explanation I. – The expression "former suit" shall denote a suit which has been decided prior to the suit in question whether or not it was instituted prior thereto.

Explanation II. – For the purposes of this section, the competence of a Court shall be determined irrespective of any provisions as to a right of appeal from the decision of such Court.

Explanation III. – The matter above referred to must in the former suit have been alleged by one party and either denied or admitted, expressly or impliedly, by the other.

Explanation IV. – Any matter which might and ought to have been made ground of defence or attack in such former suit shall be deemed to have been a matter directly and substantially in issue in such suit.

Explanation V. – Any relief claimed in the plaint, which is not expressly granted by the decree, shall, for the purposes of this section, be deemed to have been refused.

Explanation VI. – Where persons litigate bona fide in respect of a public right or of a private right claimed in common for themselves and others, all persons interested in such right shall, for the purposes of this section, be deemed to claim under the persons so litigating.