A thorough study of res judicata is of fundamental importance for understanding the functioning of the legal system and guaranteeing legal certainty in a democratic society.

In general terms, the purpose of res judicata is to guarantee the stability and security of legal relationships, preventing the indefinite reopening of already decided cases and allowing the parties to trust in the fairness of the outcome achieved.

But what exactly is res judicata?

The concept of res judicata is defined in article 502 of the Code of Civil Procedure, which characterizes it as the authority that renders a decision on the merits immutable and indisputable, without the possibility of appeal. 

It is important to emphasize that the word "authority" indicates that res judicata is not an effect of the judgment, but rather the authority of the decision on the merits that makes it indisputable and immutable. 

As long as an appeal is pending, there is no res judicata, since the appeal prevents its formation. This is because the appeals provided for in our system produce various effects, but the main one is the obstructive effect of res judicata.

Res judicata and the study of cognition. 

Before delving into the study of res judicata, it is important to recall the concept and practical consequences of cognitive theory.

In short, cognition is the level of depth that a judge possesses regarding the factual and legal issues being analyzed in a legal proceeding. 

This level can be superficial, also called summary, or in-depth, which is known as exhaustive.

The formation of res judicata in summary proceedings.

In summary proceedings, the judge does not have all the necessary information to make a definitive decision. Therefore, he renders a decision based on a judgment of probability, that is, on what he believes to be most likely. 

Since the investigation has not yet been finalized, this decision may be changed later during the process. For this reason, it does not constitute res judicata. 

How does it work in practice? 

Let's suppose a person has a serious illness and needs an expensive medication for treatment. However, this person does not have the financial means to afford the cost of the medication. 

In this case, she can file a lawsuit to request that the state provide the medication free of charge.

The judge, upon reviewing the request, may grant an urgent preliminary injunction, ordering the State to provide the medication immediately, even before the conclusion of the legal proceedings. 

This decision would be based on a summary assessment, that is, on a judgment of probability that the person truly needs the medication and that the State has a duty to provide it.

However, if new evidence or information emerges during the process indicating that the person no longer needs the medication, or that the State is not obligated to provide it, this decision may be changed. 

Therefore, the decision will not constitute res judicata, meaning it will not become final and unchangeable.

The formation of res judicata in exhaustive cognition

When a judge conducts a thorough examination, it means that he has carefully analyzed all questions of fact and law, and is certain of his decision. 

In this case, the decision may become final and no longer subject to appeal; in other words, it may become res judicata.

Suppose that John, the driver of vehicle A, and Mary, the driver of vehicle B, collided at an intersection. Mary suffered serious injuries and decided to file a civil liability lawsuit against John, alleging that he was responsible for the accident.

The judge in charge of the case conducted the procedural investigation, hearing witnesses and experts, and concluded that João was indeed at fault for the accident, due to his recklessness in running the red light. The judge then ordered João to pay compensation to Maria.

João, dissatisfied with the decision, decided to appeal to the State Court. However, after analyzing the appeals presented, the Court upheld the decision of the judge of first instance and denied João's appeal.

Having accepted the decision and chosen not to appeal, the decision became final and can no longer be modified. This means that, in this case, res judicata has been established, making the decision indisputable and immutable.

The prerequisites for the existence of res judicata.

According to legal doctrine, a judge's decision or judgment on the merits will only constitute res judicata if the procedural requirements for its existence are met. 

• Jurisdiction; 
• Initial petition, 
• Capacity to file a claim (for the author);
• Summons of the defendant (when necessary). 

If all these assumptions are present, the decision will be capable of forming res judicata, becoming immutable and indisputable. 

On the other hand, if any of these assumptions are missing, the decision will be nonexistent and will not have the force of res judicata, that is, it will not produce any effect.

The prerequisites for the validity of res judicata.

For a judgment to be considered valid, the procedural requirements for its validity must be met, such as:

• The absence of res judicata, lis pendens, or preclusion;
• The judge who issued the ruling is neither disqualified nor absolutely incompetent;
• The initial petition is ready;
• Valid service of process occurred;
• And the parties have procedural capacity. 

If any of these prerequisites are lacking, the procedural relationship is invalid and the process is null and void.

It is important to remember that the lack of any of the validity requirements may lead to the rescission of the judgment, as in cases where the final judgment or decision on the merits has been issued by a judge who was disqualified or absolutely incompetent, or in violation of res judicata. 

The IDP Online postgraduate program in Civil Procedure offers students comprehensive training on res judicata in the subject "Judgment and Res Judicata".

In this course, students will have the opportunity to deepen their knowledge of the various aspects of res judicata, such as formal and material res judicata, total and partial res judicata, and the objective, subjective, and temporal limits of res judicata. 

Furthermore, students will learn about the preclusive effect of res judicata, the relativization of res judicata, and the relationship between res judicata and ongoing legal relationships.

Study Civil Procedural Law at IDP Online!

With IDP's online course, you will have the opportunity to study from anywhere in Brazil and also interact live with renowned professors from all over the country. 

This interaction will greatly facilitate your learning, as you will have the assistance of leading experts in the field, allowing you to exchange ideas and clarify doubts in real time.

The postgraduate program in Civil Procedure at IDP is an excellent opportunity to enhance your knowledge and stand out in the job market. Don't miss this chance to invest in your career and become an even more qualified professional.

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Legislative References

Constitution of the Federative Republic of Brazil

Code of Civil Procedure (Law 13.105/15)

References

Annotated Code of Civil Procedure – 2023 Edition

Authors: Nelson Nery Junior, Rosa Maria de Andrade Nery 

Publisher: Courts Review

Annotated Code of Civil Procedure – 2023 Edition

Author: José Miguel Garcia Medina 

Publisher: Courts Review