Acquisitive Prescription: When a Builder Without Planning Permission Becomes the Landowner

Imagine: you own a plot of land in Valbonne, in the Grasse hinterland. One day, you discover that your neighbour has built a swimming pool, a garden shed, or even a house… without planning permission, and that was more than thirty years ago. You think he will have to demolish it? Not so sure. The French Supreme Court has just ruled: non-compliance with planning rules does not, in itself, prevent the possessor of the land from becoming the owner by prescription (Article 2258 of the Civil Code – the mechanism allowing acquisition of property through prolonged possession).

This decision, handed down on 21 September 2022 (appeal no. 21-17.409), is a bombshell for property law. It pitted co-owners of a plot against an occupant who had built without authorisation. The judges held that even if the construction is unlawful under planning law, it does not constitute an act of possession contrary to public policy or good morals. The result: prescription can operate, and the possessor becomes the owner. But beware, this does not mean anything goes. Analysis follows.

In this article, I will explain what this decision actually changes for you, whether you are an owner or a neighbour, in Juan-les-Pins or elsewhere. How should you react if you are concerned? What pitfalls should you avoid? Follow the guide.

Facts: A story as common as can be

The case began in Grasse, in the Alpes-Maritimes. Several people, the V. siblings, claimed to be co-owners of a plot registered under cadastral number T [Cadastre 1], located at the place known as "Localit G". This plot was occupied by Mrs [E] [R], wife of V., who had built a house without planning permission. The V. siblings sued Mrs R. for eviction and demolition of the building, arguing that it was unlawful and violated planning rules.

Mrs R. defended herself by invoking acquisitive prescription (usucapion): she had occupied the land for more than thirty years, continuously, peacefully, publicly, unequivocally, and as owner (the famous conditions of Article 2261 of the Civil Code). She produced witness statements, receipts for property taxes, invoices for works… In short, she proved that she had behaved as the true owner for decades.

The Grenoble Court of Appeal, in a judgment of 18 May 2021, ruled in favour of Mrs R.: it recognised that she had acquired the land by prescription. The V. siblings appealed to the Supreme Court. Their main argument: building without planning permission is contrary to public policy, so the possession is "unlawful" and cannot lead to prescription. The Supreme Court dismissed the appeal: it confirmed that the violation of planning rules does not render the possession "contrary to public policy or good morals" within the meaning of Article 2258 of the Civil Code. Only acts of possession that are inherently unlawful (such as violence, theft, or possession contrary to good morals) can prevent prescription.

The reasoning of the court — analysed

The Supreme Court relied on Article 2258 of the Civil Code, which states that "possession is the de facto power exercised over a thing or a right" and that it is protected by law unless it is "vicious", i.e., acquired by violence or force. The question was whether building without planning permission rendered the possession "contrary to public policy".

The lower court had already rejected this argument: it considered that non-compliance with planning rules concerns only the legality of the building, not the possession of the land itself. The Supreme Court approved this reasoning. It recalled that acquisitive prescription is a mode of acquiring ownership, independent of planning rules. In short, one can become the owner by prescription of land on which one has built without permission, but this does not regularise the building under planning law. The town council can still require demolition for violation of the local planning plan or the Planning Code.

In other words, the decision clearly distinguishes two things: the right of ownership (acquired by prescription) and the compliance of buildings (which falls under public law). However, note that the possession must satisfy all the usual conditions (peaceful, public, unequivocal, continuous). If the building was done at night, in secret, or with violence, prescription may be excluded. But mere administrative unlawfulness does not prevent it.

What few people know is that this position has been consistent since a 2004 decision (Civ. 3e, 10 March 2004, no. 02-15.578). The Supreme Court is therefore confirming its case law, without a reversal. What is new is the clarification on the concept of public policy: only inherently unlawful acts (violence, theft, etc.) vitiate possession, not breaches of planning rules.

What this means for you — practically

If you are the owner of land and your neighbour has built on it without permission for more than thirty years, you risk losing your property. Prescription is acquired if the conditions are met. For example, in Juan-les-Pins, an owner who allowed his neighbour to occupy a strip of land to build a terrace for 30 years will no longer be able to reclaim his land. undefined, I have seen cases where owners lost several hundred square metres for failing to act in time.

If you are the unauthorised occupant, this decision is good news: you can become the owner if you prove thirty years' possession. But beware, you remain exposed to criminal or administrative proceedings for building without permission. Concrete example: in Valbonne, a 100 m² house built without permission may be subject to a fine of €120,000 and a demolition order. Prescription does not protect you from that.

If you are a buyer, be wary of land that has been occupied for a long time. Before buying, check that the seller has been the registered owner in the cadastre for more than 30 years. Otherwise, an occupant could claim prescription.

Finally, if you are a tenant, note that prescription can also apply to common parts or outbuildings. For example, a tenant who has cultivated a garden for 30 years may become its owner if the owner has not reacted.

Four tips to avoid this type of dispute

• Monitor your land regularly. An annual visit can detect any unlawful occupation or construction. If you notice an encroachment, act within 30 years, otherwise you risk losing your right. Remember to take dated photos.
• Have a bailiff make a record. If you discover a building without permission, have a bailiff draw up a report. This interrupts the limitation period and proves your challenge. The cost (around €150-250) is modest compared to the value of the land.
• Start legal action quickly. Do not wait. An action for recovery (Article 544 of the Civil Code) must be brought before the prescription period expires. If you let 30 years pass, you are barred.
• Check the cadastre and notarial deeds. When buying, ask the notary for a certificate of uninterrupted ownership for 30 years. If the seller cannot provide it, demand a warranty against eviction or refuse the purchase.

Besoin d'un conseil personnalisé ? Contactez Maître Zakine — première consultation 30 min à 45€.

Further reading: related case law and developments

The Supreme Court had already ruled, in a decision of 10 March 2004 (no. 02-15.578), that violation of planning rules does not affect possession. This position was confirmed by a decision of 13 January 2016 (no. 14-28.674): building without permission is not an act of unlawful possession. The 2022 decision therefore merely confirms a well-established trend.

On the other hand, recent case law shows some strictness on the conditions of possession. Thus, a decision of 9 March 2022 (no. 20-22.447) recalled that possession must be "unequivocal": if the occupant has acknowledged another's ownership (e.g., by paying rent or accepting a boundary survey), prescription is impossible. Courts are therefore demanding on the quality of possession.

In the future, we can expect judges to be even more attentive to the proof of possession. Technologies (geolocation, satellite photos) will facilitate demonstration, but also challenge. In any event, this decision does not undermine the power of mayors to enforce planning rules. Prescription is not an automatic regularisation.

What you absolutely must remember

Practical FAQ:

1. Can I acquire land by prescription if I built on it without permission? Yes, if you have possessed it for 30 years peacefully, publicly, unequivocally, and as owner. But the building remains unlawful.
2. What should I do if my neighbour builds without permission on my land? Act quickly: have a bailiff's report made and sue him. You have 30 years to act, but the sooner you do, the better.
3. Can prescription be invoked for a recent building? No, 30 years of possession are required. If the building dates from less than 30 years ago, you can demand demolition.
4. What is the cost of a recovery action? Expect between €2,000 and €5,000 in lawyer and bailiff fees, depending on complexity. But if you win, costs may be borne by the other party.
5. Can I regularise my building without permission after prescription? No, prescription does not regularise the planning offence. You must apply for retrospective planning permission, but the town council may refuse it if the building does not comply with the local plan.

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