1. Core Legal Answer & Context: The doctrine of res sub judice (Latin for 'a matter under judgment') is a fundamental principle of civil procedure, codified in Section 10 of the Civil Procedure Code, 1908 (CPC). It mandates the stay of a subsequent suit if the matter in issue is directly and substantially in issue in a previously instituted suit between the same parties (or their representatives), litigating under the same title, and the previously instituted suit is pending in the same or any other competent court in India. The object of this doctrine is to prevent courts of concurrent jurisdiction from simultaneously entertaining and adjudicating upon two parallel litigations in respect of the same matter in issue, thereby avoiding multiplicity of proceedings, conflicting judgments, and harassment to the parties.

Conditions for applicability: (a) Two suits: A previously instituted suit and a subsequently instituted suit. (b) Matter in issue: The matter in issue in the subsequent suit must be directly and substantially the same as in the previous suit. (c) Parties: The parties in both suits must be the same or their representatives. (d) Title: The parties must be litigating under the same title in both suits. (e) Competent Court: The previously instituted suit must be pending in a court having jurisdiction to grant the relief claimed.

2. Relevant Statutes and Sections:

• Civil Procedure Code, 1908: Section 10.

3. Important Landmark Cases:

• Manohar Lal Chopra v. Rai Bahadur Rao Raja Seth Hiralal (1962): This case extensively explained the object and scope of Section 10, emphasizing its mandatory nature and the conditions for its application.

4. Clear Conclusion: Section 10 CPC embodies the doctrine of res sub judice, serving as a crucial procedural safeguard to prevent parallel litigation and conflicting decisions on the same subject matter between the same parties, thereby promoting judicial efficiency and finality.