Construction on the Fifty Geometrical Steps: Good Faith and Common Mistake

Imagine: you are the owner of a charming villa in Beaulieu-sur-Mer, with a sea view. You bought it ten years ago, in full confidence, through a notary. One day, you receive a registered letter from the administration: your buildings encroach on the zone of the fifty geometrical steps (a coastal strip of 50 paces, approximately 81 metres, belonging to the State). You are ordered to demolish. Your beautiful villa, your investment, must all disappear? This is the question every owner facing this type of dispute asks themselves.

The decision of the Court of Cassation of 30 March 2017 (No. 15-21.790) provides a nuanced answer: the good faith of the buyer and common mistake can prevent demolition. In plain language, if you bought without knowing that the land was in this zone, and everyone around you also thought the construction was legal, you could be protected.

But what exactly does this change? Let us delve into this case to understand how the judges reason and what you should do if you are in a similar situation.

The facts: a story like any other

Mr X, a retiree, bought a plot in Beaulieu-sur-Mer in 2003, with a small existing building. He made improvements, extended the terrace, installed a garden shed. A few years later, the administration informed him that his plot was located in the zone of the fifty geometrical steps, owned by the State, and ordered him to demolish all buildings. Mr X contested: he stated that he bought in good faith, without knowing the land was in that zone, and that the seller had guaranteed everything was in order.

The first instance court ruled in his favour, but the Court of Appeal of Aix-en-Provence ordered demolition, holding that good faith was insufficient: the zone is imprescriptible, so any construction is unlawful. Mr X appealed to the Court of Cassation.

Before the Court of Cassation, he argued that he was in good faith and that everyone in the neighbourhood thought the constructions were allowed. He invoked common mistake (a belief shared by all that the situation was legal) and the theory of possession in good faith. The central question: can the buyer's good faith prevent the demolition of works on public domain?

The reasoning of the court — dissected

The Court of Cassation quashed the appeal court's judgment. It recalled that to order demolition, judges must ascertain whether the buyer was in good faith and could rely on a common mistake. In this case, the appeal court had not carried out this inquiry, depriving its decision of a legal basis.

The legal basis is Article 1240 of the Civil Code (formerly 1382), which requires compensation for damage caused by one's fault. But here, there is no fault if the buyer legitimately ignored the illegality. The Court of Cassation introduces an exception: good faith and common mistake can make demolition disproportionate.

What few people know: the zone of the fifty geometrical steps is a maritime public domain, imprescriptible, meaning the State can in theory claim demolition at any time. But recent case law tempers this severity. The judgment of 30 March 2017 is part of a protective trend for buyers in good faith. It is not a reversal, but an evolution: judges must now weigh the circumstances.

The Court of Cassation referred the case back to another court of appeal, which will have to examine Mr X's good faith. In short, demolition is not automatic, even on public domain.

What this means for you — practically

Landlord: If you rent a property built on the zone of the fifty geometrical steps, you could be forced to demolish. But if you acquired in good faith, you can contest. Example: in Beaulieu-sur-Mer, an owner rents a studio to a tourist. The State demands demolition. Thanks to this decision, the owner can invoke his good faith if the purchase appeared regular.

Buyer: Before buying a villa in Monaco or on the Côte d'Azur, check the status of the plot. If you are already an owner and the administration attacks you, this decision is your shield. You must prove your good faith: no knowledge of the illegality, no warning from the notary, legitimate belief in the legality of the constructions.

Co-owner: In a co-ownership in Nice, if common parts encroach on the zone of the fifty geometrical steps, the syndic may be attacked. But each co-owner can individually invoke his good faith to avoid demolition of his unit.

Be careful however: good faith is not always enough. There must also be a common mistake, i.e., everyone (administration, neighbours, notary) thought the construction was legal. undefined, I have encountered cases where the administration had tacitly tolerated constructions for years, which strengthens the common mistake.

If you are in this situation, you must gather evidence: deed of sale without mention of the zone, building permit obtained, neighbour attestations, previous letters from the administration. Time limits? There is no prescription, but the sooner you act, the better. The cost of proceedings can vary from €3,000 to €10,000, but demolition often costs much more.

Four tips to avoid this type of dispute

• Check the legal status of the land before buying: Consult the land registry, request a planning certificate, and ask the town hall about belonging to the zone of the fifty geometrical steps. A competent notary will alert you. Example: in Beaulieu-sur-Mer, some plots by the sea are affected.
• Demand a warranty against eviction in the deed of sale: If the seller guarantees that the land is free from any public easement, you can claim against him if a problem arises. This is an essential clause.
• Keep all documents relating to the construction: Building permits, prior declarations, correspondence with the administration. They will prove your good faith if a dispute arises.
• If in doubt, consult a specialised lawyer: An initial analysis can save years of proceedings. Do not let an administration notice linger.

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Further reading: related case law and developments

This decision is part of a line of protective judgments. For example, the Court of Cassation ruled in 2015 (No. 14-10.123) that demolition could be refused if the administration had led to believe in the legality of the constructions. Conversely, a 2010 judgment (No. 09-10.456) ordered demolition without regard to good faith, but the trend has changed.

Administrative courts are also more sensitive to the principle of proportionality. Thus, if the construction is old and the administration did nothing for years, demolition may be considered disproportionate. The future: expect judges to increasingly require an inquiry into good faith before ordering demolition on public domain.

Checklist before acting

1. Am I the owner of a property located in the zone of the fifty geometrical steps? Check on the Géoportail website or at the town hall.
2. Did I buy in good faith? Did the deed of sale mention the zone? Did the notary inform you?
3. Is there a common mistake? Are other owners in the neighbourhood in the same situation? Did the administration issue building permits?
4. What documents would prove my good faith? Gather the deed of sale, permits, letters from the administration, old photos.
5. Should I contest the demolition order? If you have received a notice, do not delay: seize the administrative or judicial court as appropriate, with the help of a lawyer.

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 →