In Raju Ramsing Vasave v. Mahesh Deorao Bhivapurkar (2008) 9 SCC 54
The Supreme Court has laid down 3 exceptions to the rule of Res Judicata
(i) When judgment is passed without jurisdiction
(ii) When matter involves a pure question of law.
(iii) When judgment has been obtained by committing fraud on the Court.
Fatima Bibi Ahmed Patel v. State of Gujarat (2008) 6 SCC 789 – Res Judicata principle not applicable to criminal cases
LACK OF JURISDICTION
The doctrine would not apply if the judgment is by a Court lacking inherent jurisdiction or when the judgment is non-speaking. (Vide Union of India v. Pramod Gupta (Dead) by L.Rs. & Ors., (2005) 12 SCC 1).
DECISION WITHOUT MERIT
In State of Uttar Pradesh & Anr. v. Jagdish Sharan Agrawal & Ors., (2009) 1 SCC 689, the Apex Court held that where the matter has not been decided on merit earlier, the doctrine of res judicata is not applicable.
The principle of res judicata would not apply if the decree has been obtained by practicing misrepresentation or fraud on the court, or where the proceedings had been taken all together under a special Statute. More so, every finding in the earlier judgment would not operate as res judicata. Only an issue “directly” and “substantially”, decided in the earlier suit, would operate as res judicata. Where the decision has not been given on merit, it would not operate in case against the judgment and decree of the court below the appeal is pending in the appellate court, the judgment of the court below cannot be held to be final, and the findings recorded therein would not operate as res judicata.
(See : Premier Cable Co. Ltd. v. Government of India, AIR 2002 SC 2418; Arm Group Enterprises Ltd. v. Waldorf Restaurant, (2003) 6 SCC 423; Mahila Bajrangi v. Badribhai, (2003) 2 SCC 464; Pondicherry Khadi & Village Industries Board v. P. Kulothangan, AIR 2003 SC 4701; Kiran Tandon v. Allahabad Development Authority, AIR 2004 SC 2006; T.P. Moideen Koya v. Govt. of Kerala, (2004) 8 SCC 106; State of Haryana v. State of Punjab, (2004) 12 SCC 673; Bhanu Kumar Jain v. Archana Kumar, (2005) 1 SCC 787; Sampat Co-operative Sugar Mills Ltd. v. Ajit Singh (2005) 3 SCC 516; and Swami
Atmananda & Ors. v. Sri Ramkrishna Tapovanam & Ors. AIR 2005 SC 2392).