What does 'res judicata' prevent in legal cases?

'Res judicata,' also known as claim preclusion, is a legal doctrine that prevents a party from re-litigating the same issue or claim that has already been resolved in a final judgment by a competent court. The primary purpose of this principle is to ensure the finality of decisions, promote judicial efficiency, and protect parties from the burden of multiple lawsuits over the same matter.

When a case is resolved and reaches a final judgment, the parties involved are barred from bringing subsequent actions that arise from the same facts or occurred during the same circumstances. This means that even if new arguments or evidence were to emerge, the underlying issue has been conclusively determined and cannot be contested again in court.

The other options focus on aspects that are not directly related to the primary function of res judicata. For example, it does not prevent future modifications to settled cases, nor does it deal with court order enforcement or the introduction of new evidence in appeals. Each of these scenarios falls under different legal principles and rules. Thus, 'B' accurately captures the essence of what res judicata is designed to protect against.