This article is general information, not legal advice. Expropriation disputes are intensely fact-specific – the value of a single parcel can turn on the diameter of a pipe – so speak to a French avocat before acting on anything below.
Last Updated: July 2026
When a French public authority takes your land, the Constitution promises you a juste et préalable indemnité – fair compensation, paid before they move in – and then the arithmetic begins. Whether your parcel counts as a terrain à bâtir (building land) or as something humbler is the single question that moves the price more than any other, and until last month an expropriating authority could deny you that label because of pipes and cables serving a different site, on the far side of the commune, that you had never seen. On 19 June 2026 the Conseil constitutionnel closed that door (n° 2026-1206 QPC), and if you own land anywhere near a French development zone, the small print deserves ten minutes of your attention.
Two words that move the price: what terrain à bâtir does to your indemnity
French expropriation compensation is built on article 17 of the 1789 Declaration of the Rights of Man, which the Conseil reads as requiring an indemnity covering the entire direct, material and certain loss caused by the taking. If you and the authority cannot agree on a figure, either side can bring the dispute before the juge de l’expropriation, a specialised judge who fixes the indemnity under the rules of the expropriation code – and who begins, in practice, by deciding what kind of land is being taken.
Under article L. 322-3 of the expropriation code, land only qualifies as a terrain à bâtir if it clears two hurdles at once. It must sit in a sector a planning document designates as constructible, assessed at the code’s date de référence. And it must be effectively served – by an access road, an electricity network, drinking water and, where planning or public-health rules require it for building, sewerage – with those networks in the immediate vicinity of the parcel and sized to match what could actually be built on it. Fail either test and the land is valued by its existing use, which for a field means a field, however glorious the mairie’s plans for the neighbourhood.
The zone rule, and the strange geometry of the multi-site ZAC
The second sentence of article L. 322-3, 2° adds a twist that sounds technical and decides fortunes: where land sits in a zone earmarked by a planning document for a comprehensive development operation (opération d’aménagement d’ensemble), the adequacy of those networks is measured against the whole zone rather than the parcel. The logic is defensible in a compact zone – the constructibility of each plot genuinely depends on equipment planned for the ensemble – and the Conseil accepted that the legislator was pursuing a legitimate aim in stopping public land purchases being priced up unjustifiably.
The trouble started with the zone d’aménagement concerté, or ZAC, which the planning code allows to be created across several territorially distinct sites at once. The Cour de cassation had held, in decisions of 27 May 2021 (n° 19-25.939) and 8 February 2023 (n° 22-10.143) cited by the Conseil itself, that the whole-zone yardstick applied to these multi-site ZACs too – so the networks serving your site were measured against sites that might be kilometres away, non-contiguous, and equipped to a completely different standard. A parcel in a coherent, fully serviced sector could be refused building-land status because a distant limb of the same administrative creature lacked a sewer, and the commentary in Dalloz points out the sharpest edge of the problem: neighbouring plots had in some cases already been sold, on the open market, at building-land prices.
Two owners, one QPC: the question that reached the rue de Montpensier
That is precisely the situation two owners found themselves in when their parcels were expropriated for a multi-site ZAC and the amicable offer did not convince them. Before the expropriation judge they raised a question prioritaire de constitutionnalité – the French mechanism for challenging a statute’s constitutionality mid-litigation – arguing that the provision, as read by the Cour de cassation, let the authority undervalue their land using the characteristics of somebody else’s. The Cour de cassation found the question serious enough to refer on 10 April 2026, and the Conseil constitutionnel answered on 19 June.
Valid – but only just: the réserve that rewrites the test
The Conseil declared the provision constitutional, which sounds like a defeat for the owners until you read the réserve d’interprétation – a binding condition on how the text may ever be applied – attached at paragraph 15 of the decision:
« Les dispositions contestées doivent être interprétées comme imposant à l’autorité expropriante, sous le contrôle du juge, d’apprécier la dimension des réseaux desservant une zone d’aménagement concerté multi-sites au regard de l’ensemble de la zone dans le seul cas où les différents sites à l’intérieur de son périmètre ont vocation à être desservis par de mêmes réseaux ou dépendent d’une capacité commune. Dans le cas contraire, la dimension des réseaux doit être appréciée au regard de chaque site […]. »
“The contested provisions must be interpreted as requiring the expropriating authority, subject to the court’s review, to assess the dimension of the networks serving a multi-site ZAC against the zone as a whole only where the various sites within its perimeter are intended to be served by the same networks or depend on a shared capacity. Otherwise, the dimension of the networks must be assessed site by site […].” – Conseil constitutionnel, 19 June 2026, n° 2026-1206 QPC, § 15 (our rendering)
The mechanics matter, because a réserve of this kind is not a polite suggestion: from publication it binds every authority and every court applying the text. The whole-zone yardstick survives only where the sites of a multi-site ZAC are actually meant to share the same networks or draw on a common capacity, and everywhere else the assessment reverts to your site – or, where clusters of sites genuinely share their plumbing, to each cluster taken separately. In the Dalloz commentary’s summary, a parcel can no longer be refused the terrain à bâtir label solely because another site of the ZAC is inadequately served, so long as its own site is properly equipped.
| Your situation | The networks are now measured against |
|---|---|
| Zone designated for comprehensive development, single site | The whole zone, as before |
| Multi-site ZAC where the sites share the same networks or a common capacity | The whole zone |
| Multi-site ZAC where your site runs on its own networks | Your site alone |
| Multi-site ZAC with clusters of sites sharing networks | Each cluster, taken separately |
What this means when the letter arrives
If a ZAC is coming your way, the first document worth reading is the zone’s creation file, because everything now hangs on its geography: whether the ZAC is multi-site, which networks are planned to serve which sites, and whether your site shares capacity with the others. The decision also restates two safeguards that were easy to miss in the noise. The burden of proof of the networks’ insufficiency sits with the expropriating authority where the zone rule applies, as the Cour de cassation confirmed on 8 January 2026 (n° 24-22.726). And the expropriation judge can disregard administrative servitudes and restrictions on your land where their creation reveals a dolosive intent on the expropriant’s part – the polite legal term for rigging the valuation.
Beyond that, the practical playbook is the one we set out when an appeal court added a lost-rent indemnity on appeal: never treat the amicable offer as a fait accompli, and gather the comparables, especially neighbouring plots that sold at building-land prices. Remember too that the existence, proximity and capacity of networks are questions of fact on which trial judges have the final word – the evidentiary file you build matters more than the rhetoric. Owners with property already in a dispute should raise the réserve now, since it governs how the provision may be applied in proceedings that are still open. And if your land sits near a zone but your worry is the opposite one – a property left to decay until the commune steps in – the constitutional rules on that were tested in May 2026 too.
We read the decisions so you can read the bill. If a ZAC has appeared on your commune’s planning map and you are wondering what it does to your land’s value, the comments are open, and the contact page reaches us directly.
FAQ
What is a terrain à bâtir in French expropriation law?
It is land that, at the statutory reference date, is both designated as constructible by a planning document and effectively served by an access road, electricity, drinking water and, where required for building, sewerage – with the networks in the immediate vicinity and sized to the land’s building capacity. The label commands a building-land valuation; without it, the land is valued by its existing use.
What is a multi-site ZAC?
A zone d’aménagement concerté is a public development zone, and French planning law allows a single ZAC to be created over several territorially distinct, non-contiguous sites. Before the 2026 decision, the adequacy of networks serving any one site was assessed against the entire multi-site zone.
What exactly did the Conseil constitutionnel decide on 19 June 2026?
It upheld the second sentence of article L. 322-3, 2° of the expropriation code, but under a binding réserve d’interprétation: the whole-zone assessment of networks applies to a multi-site ZAC only where its sites are meant to be served by the same networks or depend on a common capacity. Otherwise the assessment is made site by site, or per group of sites sharing networks.
Who must prove the networks are insufficient?
Where land sits in a zone designated for comprehensive development, the expropriating authority bears the burden of proving that the networks’ dimension is insufficient, as the Cour de cassation confirmed in January 2026. The existence, proximity and capacity of the networks remain questions of fact for the trial judges.
