Definition - What does Res Judicata mean?
Res judicata is a Latin term that means "a thing [already] judged."
In the context of the law, res judicata refers to a matter that has been decided formally and that cannot be brought to trial again. In other words, res judicata means that a plaintiff cannot bring an identical complaint to a court after a final ruling has been made on that same issue.
Res judicata is designed to prevent the repetition of the same trials and consequently time wasted in the courts.
Justipedia explains Res Judicata
The reason why the principle of res judicata exists is because without it, a plaintiff could file the same lawsuit against the same defendant as many times as they would like.
For example, if a person sues their neighbor for a causing a nuisance, gets a verdict and then attempts to sue the same neighbor for the same nuisance, res judicata would become relevant. In such a case, the court would dismiss the issue and refer the plaintiff back to the original trial and the original verdict.
So, once a lawsuit has concluded, the exact same issue can never be brought to court again in a new trial by the same plaintiff.