Res judicata: when does a court decision prevent you from taking further action?

In our previous article, we explored the fundamental principle of res judicata: the idea that a case decided by the courts should not, as a general rule, be tried again. It is a pillar of our legal system, ensuring stability and social peace. But what does this mean in practical terms for you? If you have lost a case, can you simply reformulate your claim or use a different argument to try your luck again? Conversely, if you have obtained a favourable decision, are you completely safe from your opponent bringing a new action on the same subject?

The answer lies in one of the key aspects of res judicata: its authority. More specifically, its negative impactenshrined in the saying Non bis in idem (not twice for the same thing), prohibits the resubmission of a case to the courts identical to one that has already been decided. But what is an "identical" case in the eyes of the law? And what are the consequences if you forget to present all your arguments at the first trial? This article goes to the heart of these practical questions.

The principle: the same case cannot be tried twice (Non bis in idem)

Res judicata functions as a procedural defence mechanism. It enables a party (or sometimes the judge) to block a new legal claim that would seek to re-litigate what has already been decided.

Res judicata as a procedural shield

When one party attempts to bring a new legal action on a matter that has already been decided by a decision that is at least final (i.e. not subject to appeal, for example), the other party may raise what is known as an "objection". plea of inadmissibility based on res judicata. This is provided for in article 122 of the Code of Civil Procedure.

It asks the judge to declare the new application inadmissible, without even examining its merits. The judge simply notes that the case has already been decided and that it is not possible to reopen it. The aim is clear: to ensure the stability of past decisions, to protect the party who has already obtained a final judgment from judicial harassment, and to guarantee the proper administration of justice by avoiding redundant proceedings.

Who can invoke res judicata?

Traditionally, it is up to the party who benefits from the first decision (generally the defendant in the new proceedings) to raise this objection. They must prove that a previous decision has already resolved the same dispute.

However, since a 2004 reform, article 125 of the Code of Civil Procedure allows the judge to ex officio This means that even if none of the parties so requests, the court may itself decide to declare the new claim inadmissible. This means that even if none of the parties requests it, if the judge is aware of a previous decision deciding the same case between the same people, he can decide of his own accord to declare the new claim inadmissible. However, this possibility remains an option for the judge, not an obligation, except in very specific cases (for example, if the first decision emanates from the same lawsuit). In practice, therefore, it is always preferable for the party concerned to actively raise this defence.

The essential condition: triple identity (article 1355 of the Civil Code)

For res judicata to apply, it is not enough for the two cases to be similar. The law requires a strict condition, set out in article 1355 of the Civil Code: there must be a triple identity between the first case decided and the new claim. The two actions must have the same subject matter, the same cause of action and be brought by the same parties acting in the same capacity. If only one of these conditions is missing, res judicata does not apply and the new action can be examined.

Identity of purpose: asking for the same thing

The object of the claim is specifically what is being asked of the judge. For there to be identity of purpose, the new action must be aimed at obtaining the same advantage or the same result as the first.

For example:

• A claim for payment of an unpaid invoice is not the same as a subsequent claim for damages for loss caused by late payment.
• An action to have a contract annulled (for example, for lack of consent) does not have the same object as an action to have it rescinded (for example, for non-performance by the other party).
• A claim for compensation for injury A (e.g. medical expenses following an accident) does not have the same object as a claim for a separate injury B (e.g. non-material injury) arising from the same accident, even if this is qualified by the rule of concentration that we shall see later.

The assessment of identity of purpose can sometimes be subtle and depends on the specific circumstances of each case.

Identity of cause: relying on the same reasons

The cause of the claim is the legal and factual basis for the claim. Why are we asking for this or that? This is the combination of the relevant facts and the rule of law invoked. For there to be identity of cause, the new claim must be based on the same grounds as the first.

This is where an essential distinction comes into play, and a major development in case law:

• Recent developments : If important and relevant events occur after the first decision, or if they already existed but were only discovered later through no fault of the party concerned, they may constitute a new cause of action. In this case, a new action is possible. The classic example is the aggravation of a personal injury after an initial compensation judgment: the victim may claim additional compensation for this aggravation.
• New ways of proving old facts : Discovering new evidence (a testimony, a document) concerning facts that already existed at the time of the first trial does NOT constitute a new case. If you lost because you failed to prove a fact, finding the evidence later does not entitle you to start the same trial over again.
• New legal arguments : This is the point that has changed the most. For a long time, it was considered that invoking a different rule of law (for example, contractual liability after having failed in tort) for the same claim constituted a new cause of action. This is no longer the case. no longer the case today.

Identity of the parties (acting in the same capacity)

Lastly, the decision handed down in the first case is only binding on those who were involved in it. parties (or who were legally represented, such as a minor by his parents or a company by its director). For res judicata to apply, the new action must be brought against exactly the same natural or legal persons.

In addition, these parties must act in the same capacity. What does this mean? A person may take legal action in a personal capacity, but also as the representative of another person or entity (legal representative of a child, company director, agent, etc.). If the capacity in which the person acts changes between the two lawsuits, there is no identity of party. For example, a decision handed down against Mr X acting in his personal name will not have the force of res judicata in a lawsuit in which he is acting in his capacity as manager of SARL Y.

The golden rule: say everything at the first trial (concentration of resources)

This is undoubtedly the most important development in recent years concerning res judicata. It directly affects the concept of identity of cause and has major practical consequences for anyone taking legal action.

Developments in case law (Cesareo ruling 2006)

As mentioned above, it used to be the case that a rejected claim could be reintroduced if it was based on a different rule of law. For example, if a claim for payment based on a contract failed, a new action based on unjust enrichment could be attempted.

This possibility was closed by an important decision of the Plenary Assembly of the Court of Cassation (the so-called "Cesareo" decision) in 2006. The Court established a new and strict principle: it is the responsibility of the claimant to present, at the time of the first claim, all of the arguments (factual and legal) that he or she considers to be relevant to the claim.

In other words, you can no longer "keep arguments in reserve" for a possible second lawsuit if the first fails. If a legal argument could have been used to support your initial claim, but you did not do so, you will no longer be able to use it later to justify a new action with the same object and opposing the same parties. The case is now considered to be unique for a given claim, encompassing all possible legal grounds based on the facts known at the time of the trial.

Why this rule?

This major change has a number of objectives:

• Fair debate : Encourage the parties to lay their cards on the table from the outset.
• Efficiency of justice : Avoid multiple lawsuits over the same issue with different arguments, which clogs up the courts and delays the handling of other disputes.
• Greater legal certainty : Enable the defendant to determine the final outcome of the dispute more quickly.
• Making litigants accountable : Encourage them to prepare their application thoroughly from the outset.

Practical consequences for you

This obligation to concentrate resources has direct and important implications:

1. Crucial initial preparation : Before taking any action or defending yourself, a full analysis of all the possible legal bases is essential. Every possible angle of attack or defence must be considered from the outset.
2. No legal "second chance": If you forget to invoke a relevant legal argument (even if you did not think of it initially), you will generally not be able to use it to relaunch the same claim at a later date. Res judicata will apply.
3. The importance of legal advice : Calling in a competent lawyer from the outset of the case has become even more essential to ensure that all the relevant arguments are identified and presented to the judge.
4. Distinction between pleas and claims : It is important to note that this rule applies to resources (arguments) for a request given. It does not require (apart from specific exceptions such as divorce or partition) that the following be formulated all requests arising from the same facts in a single trial. If you have several separate claims (with different subject matters) arising from the same factual situation, you could, in theory, present them in separate trials, although this is often not strategically wise.

The obligation to concentrate resources therefore considerably strengthens the authority of res judicata and underlines the need for a rigorous and comprehensive procedural approach at first instance.

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Res judicata, which is governed by the triple identity rule and reinforced by the obligation to concentrate resources, is a powerful mechanism that prevents a case that has already been decided from being tried again. Understanding its contours is essential to assess your chances of success in a new action or to defend yourself effectively if someone tries to take you to court again for the same facts.

The authority of res judicata and the obligation to concentrate resources are strict rules. An in-depth analysis of your situation by our firm is essential before initiating proceedings or if you are faced with a new action after an initial judgment.

Sources

• Civil Code: article 1355 (formerly 1351).
• Code of civil procedure: articles 122, 125.
• Case law of the Cour de cassation (in particular Assemblée Plénière, 7 July 2006, no. 04-10.672, known as the "Cesareo" judgment).