Res Judicata and Real Property Claims: A Subtlety That Changes Everything

Imagine: you own a house in Vandoeuvre-lès-Nancy, with a lovely garden overlooking the Meurthe. One day, you notice that your neighbour has erected a fence that clearly encroaches on your land. You ask him to remove it. He refuses, arguing that a judgment handed down ten years ago already dismissed your claim for recovery. You are convinced that that judgment was not based on the same grounds. Who is right? This is exactly the type of question the Court of Cassation decided in 1974.

But what difference does it actually make? A lot. This decision, delivered by the civil chamber of the Court of Cassation on 26 February 1974 (appeal no. 72-14.823), establishes a fundamental principle: res judicata only applies if the claims are identical in their object, cause, and parties. In this case, a claim for recovery based on acquisitive prescription of thirty years (former article 2262 of the Civil Code) does not have the same cause as a claim for recovery based on a title deed. Result: the former cannot be used to block the latter.

If you are an owner, tenant or property professional, this distinction can save you from losing a case on a misunderstanding. Let us look at the details of the case, then what it means for you in practice.

The Facts: An Everyday Story

Mr X, owner of a plot in Vandoeuvre-lès-Nancy, not far from the Meurthe, sees his neighbour, Mr Y, erect a fence that encroaches on his property. Mr X sues Mr Y to obtain removal of the encroachments, determination of their extent, assessment of damage and damages.

But Mr Y raises a significant argument: a previous judgment, which has become res judicata, had already dismissed Mr X's claim for recovery of real property. Mr Y therefore invokes res judicata (article 1351 of the Civil Code, now article 1355) to defeat the new claim.

The court finds in favour of Mr Y: the Nancy Court of Appeal, in a judgment of 5 July 1972, holds that the previous decision had already decided the issue of ownership, and that Mr X cannot revisit this point. Mr X then appeals to the Court of Cassation.

Before the Court of Cassation, Mr X argues that the two claims did not have the same cause: the first was based on acquisitive prescription of thirty years (he claimed to have acquired ownership by possession for thirty years), while the second is based on his title deed (the notarial deed establishing that he is the owner). The Court of Cassation agrees with him and quashes the Court of Appeal's judgment.

The Reasoning of the Court — Analysed

The Court of Cassation relies on article 1351 of the Civil Code (former), which provides that res judicata only applies to what was the subject of the judgment, and that the thing claimed must be the same, the claim must be based on the same cause, and between the same parties.

In short, for res judicata to be invoked, three conditions must be met:

• Identity of object: the claim must relate to the same thing (here, the claim for the same plot).
• Identity of cause: the legal basis of the claim must be the same.
• Identity of parties: the parties must be the same.

In this case, the cause differs: in the first action, Mr X invoked acquisitive prescription of thirty years (a method of acquisition by prolonged possession); in the second, he invoked his title deed (a notarial deed). These are two distinct legal bases. Therefore, the condition of identity of cause was not satisfied, and the Court of Appeal could not oppose res judicata.

What few people know is that the Court of Cassation is very strict on this condition. It considers that the cause is an essential element of the claim, and a change of basis is sufficient to exclude res judicata. This rigour protects litigants against overly broad decisions that would block any subsequent action on different legal bases.

However, be careful: it is not enough to change the basis to revive a case already lost. The courts check that the new cause is genuinely different and not a mere artifice to circumvent res judicata.

What This Means for You — In Practice

This decision has important practical implications for owners and property professionals.

• For the landlord or buyer: if you have lost a claim for recovery based on possession, you can bring a new one based on your title deed. For example, you have a notarial deed establishing your ownership, but your claim based on acquisitive prescription of thirty years was dismissed. You can act again on the basis of your title. This is a valuable safety net.
• For the tenant: even if you are not the owner, this decision may indirectly affect you. If your landlord claims a property against a third party, he can combine the bases (title, prescription) without being blocked by a prior decision.
• For the co-owner: in a dispute over a common or private part, the distinction between causes may allow a claim to be revived if the first basis was wrong. For example, you have been dismissed from a claim based on the co-ownership rules, but you could act on the basis of your title deed.

Let us take a concrete example in Dombasle-sur-Meurthe: an owner, Mr Dupont, lost a claim for recovery against his neighbour in 2020, based on acquisitive prescription of thirty years (he failed to prove thirty years of possession). In 2023, he finds the 1950 sale deed proving he is indeed the owner. Thanks to this case law, he can bring a new claim based on his title, without res judicata being raised against him. He will succeed, and the neighbour must remove his fence and pay damages (approximately €5,000 for the encroachments, plus bailiff's costs).

If you are in this situation, you must distinguish the basis of your claim and not hesitate to invoke another if the first has failed. A consultation with a specialist lawyer will help you determine whether the cause is genuinely different.

Four Tips to Avoid This Type of Dispute

• Call a chartered surveyor as soon as you have the slightest doubt about the boundaries of your property. An amicable boundary determination can avoid years of proceedings. In Dombasle-sur-Meurthe, the cost of a boundary survey is about €1,500, much less than a trial.
• Keep all your title deeds and notarial acts in a safe place. Digitise them and keep several copies. A lost title can compromise a claim for recovery.
• If you lose a first case, do not give up: analyse with your lawyer whether another legal basis exists. As this decision shows, a rejected thirty-year prescription does not prevent a claim based on a title.
• In case of encroachment, act quickly. The longer you wait, the more your adversary can invoke acquisitive prescription (prolonged possession). In France, acquisitive prescription is thirty years for immovable property (article 2262 of the Civil Code).

Further Reading: Related Case Law and Developments

This 1974 decision is consistent in the case law of the Court of Cassation. For example, a judgment of 19 March 1997 (appeal no. 95-14.823), where the Court recalled that res judicata cannot be raised when the cause of the claim is different, even if the object is identical. Similarly, a judgment of 12 July 2005 (appeal no. 04-10.642) specified that the cause consists of the legal basis of the claim, not the facts supporting it.

The trend of the courts is therefore very protective of owners' rights: a first failure on one basis does not close the door to a claim on another basis. This encourages litigants to be precise in the legal characterisation of their claim.

For the future, this case law remains relevant. With the reform of prescription in property matters (law of 17 June 2008), acquisitive prescription for immovable property changed from thirty to ten years for good faith acquirers, but the principle of res judicata has not changed. Lawyers must therefore always be vigilant as to the cause invoked.

Key Points to Remember

• Res judicata only blocks a new claim if the object, cause, and parties are identical.
• A claim based on thirty-year prescription and a claim based on a title deed have different causes.
• If you have lost a case on one legal basis, you can bring another on a different basis.
• Keep your title deeds and have encroachments noted by a bailiff or surveyor.
• Consult a lawyer before bringing a claim to determine the best basis.

Are you in a similar situation? A first 30-minute consultation with Maître Zakine (€45) can save you months of proceedings — and often much more. Book an appointment →