Doctrine of Res Judicata is based on the Maxim “nemo debit vis vexari pro una et endem causa”. The rule of res judicata provides no one ought to be troubled twice for one and same cause and interest. It is based on two principles, Namely, public policy that is, there should be an end to litigation and other hand to avoid hardship on the individual. In absence of this doctrine there would be no end to litigation and malicious litigant always achievers his success in vexing his poor opponent by filing repetitive suits in the court and such situation must be prevented by rule of law. Section 11 of Civil Procedure code restricts to file another suit in respect of same cause of action and same suit property and between same parties. If once a matter is finally decided by a competent court, no party can be permitted to reopen it in a subsequent litigation by filing fresh suit. The rule of res judicata is combined result of public policy and public interest. The principle is founded on justice, equity and goods conscience. There must be an end to every litigation. Thus, it applies to civil suits, partition suits, execution proceedings, arbitration proceedings, taxation matters, industrial adjudication, writ petitions, administrative orders, interim orders, criminal proceedings, compensation recovery etc. The rest judicata restricts the abuse of process of court and bar to further suit in same matter in issue and has been heard and finally decided by competent court. Our Constitution formed the fundamental right, which talks about protection from double jeopardy. Protection against double jeopardy is given in Article 20(2) of the Constitution. This clause embodies the common law rule of Nemo debet vis vexari which means that no man should be put twice in peril for the same offence. If he is prosecuted against for the same offense for which he has already been prosecuted he can take complete defence of his former acquittal or conviction. Therefore, res judicata is a protective law. It helps in reducing multiplicity of the cases. This principle can be used to prevent contradictions in the field of justice. Thus, res judicata is preferred not only in the courts of India but through all over the world.