Criminal Planning Law: When the Investigating Judge Rules on Planning Offences

Imagine you are an owner in Tarnos, in the Landes. You have undertaken extension works on your house without obtaining the precious building permit. One day, you receive a summons from the investigating judge for a planning offence. Panic ensues! But is this normal? Can the investigating judge really rule on this type of dispute?

This is a question many owners in the Landes ask themselves. Between house extensions in Saint-Paul-lès-Dax and land developments in Tarnos, planning offences are commonplace. But who has jurisdiction to judge them? The mayor? The administrative court? Or the criminal judge?

The Court of Cassation answered this question clearly in a ruling of 10 January 1980. This decision, although over 40 years old, remains highly relevant for all those considering works. It draws a red line between what falls under administration and what falls under criminal justice. But what exactly does this change for you, as an owner or real estate professional?

The facts: a story that happens every day

Let's go back to 1979, somewhere in France. Mr Dupont, owner of a plot of land, decides to construct a building without having obtained the required authorisation. He perhaps thinks no one will see it, or that the administrative formalities are too burdensome. Mistake! The mayor of his municipality notes the offence and refers the matter to the public prosecutor.

The facts are simple: construction without a permit, a clear violation of the planning code. But here is where things get complicated. The public prosecutor decides to open a judicial investigation and entrusts the case to an investigating judge. This magistrate, usually responsible for investigations in criminal cases, finds themselves having to investigate a planning offence.

Mr Dupont challenges this procedure. He believes the investigating judge does not have jurisdiction over this type of offence. According to him, Article L. 480-2 of the planning code does not expressly provide for this possibility. He therefore files an appeal, arguing that only the criminal court should be directly seized, without a prior investigation phase.

The case goes up to the Court of Cassation. The stakes are high: if Mr Dupont is right, this would mean that thousands of investigation procedures in planning matters would be irregular. But if he is wrong, then the investigating judge retains a key role in the repression of planning offences. The suspense is at its peak!

The court's reasoning — dissected

The Court of Cassation, in its ruling of 10 January 1980, dismisses Mr Dupont's appeal. The judges of the highest French judicial court develop a two-step reasoning, as clear as it is implacable.

Firstly, they examine Article L. 480-2 of the planning code. This article provides for criminal sanctions for planning offences. But what does it say exactly? The text lists the penalties incurred (fines, and even imprisonment in some cases), but does not specify which court has jurisdiction to investigate and judge these offences.

Secondly, the Court applies the general principle of criminal procedure. In short, when a text does not provide for a specific procedure, common law applies. Now, in common criminal law, the investigating judge has jurisdiction to investigate all criminal offences (i.e., offences punishable by imprisonment of up to 10 years).

In other words, the absence of express mention in Article L. 480-2 does not mean the investigating judge lacks jurisdiction. On the contrary! Since the planning code does not provide for a derogatory procedure, the ordinary criminal procedure applies. And this ordinary procedure allows the investigating judge to be seized.

The Court thus quashes Mr Dupont's main argument. It recalls that the legislator, if it had wanted to exclude the investigating judge's jurisdiction, would have expressly indicated so in the text. The silence of the law therefore amounts to acceptance of common law jurisdiction.

This reasoning is in line with established case law. It is not an innovation, but a confirmation: the investigating judge remains the guardian of individual liberties, even in planning matters. Their intervention ensures a contradictory and balanced investigation, protecting both the public interest (respect for planning rules) and defence rights.

What this changes for you — concretely

But beyond legal considerations, what does this decision mean for you, as an owner, tenant, or real estate professional? The answer is more important than it seems.

If you are a landlord in Saint-Paul-lès-Dax and have carried out works without authorisation, know that you risk not only an administrative fine, but also a criminal procedure. And this procedure can be investigated by an investigating judge. Concretely, this means more thorough investigations, possible searches, and a procedure that can last several months, or even several years.

Take a numerical example: you have built a 20 m² conservatory without a permit in Tarnos. The administrative fine can reach €1,200 per m², i.e., €24,000. But if the public prosecutor decides to refer the matter to the investigating judge, you risk in addition a criminal fine of up to €300,000, and even six months' imprisonment in the most serious cases. The bill becomes steep!

If you are a purchaser of a property, this decision also concerns you. How to react? Before buying, systematically check the planning compliance of the property. Ask to see all building permits, prior declarations, and certificates of conformity. A property that has been subject to a procedure before the investigating judge can see its value decrease by 10 to 20%, not to mention regularisation costs.

For co-owners, vigilance is essential. If works are carried out in the common parts without authorisation, all co-owners can be prosecuted. undefined, I have encountered cases where a simple air conditioning installation on the façade led to two years of procedure before the investigating judge.

Be careful, however: this jurisdiction of the investigating judge is not automatic. The public prosecutor can also decide to refer the matter directly to the criminal court, without an investigation phase. It all depends on the complexity of the case and the seriousness of the facts.

Four tips to avoid this type of dispute

• Always anticipate authorisations: before starting the slightest work, even minor, consult the planning department of your town hall. In Tarnos as in Saint-Paul-lès-Dax, rules can vary by sector. Better to lose a month obtaining a permit than five years regularising a situation.
• Document everything: carefully keep all authorisations, plans, estimates, and exchanges with the administration. In case of an inspection, you can prove your good faith and the regularity of your steps.
• Call on a professional: architect, engineering firm, or specialised lawyer. The cost of these services (budget €1,000 to €3,000 depending on the importance of the works) is negligible compared to fines and procedure costs.
• React quickly if there is a problem: if you receive a formal notice or summons, do not delay. Time limits in planning matters are short (often 2 to 4 months to contest). A quick reaction can allow an amicable regularisation, thus avoiding appearing before the investigating judge.

Deep dive: related case law and developments

The 1980 ruling is part of consistent case law. Already in 1975, the Court of Cassation had affirmed the principle of the investigating judge's jurisdiction in complex offences. This position has been confirmed many times, notably in a 1995 ruling that clarified the conditions for referral.

What few people know is that this case law has evolved over time. While the principle remains the same (the investigating judge has jurisdiction), courts today tend to favour simplified procedures for minor offences. For example, for a construction of less than 20 m² without a permit, it is rare for the investigating judge to be seized.

The current trend is towards partial de-judicialisation. Increasingly, town halls use administrative procedures (formal notice, penalty payment) rather than criminal prosecutions. But beware: this evolution does not diminish the seriousness of offences. An illegal construction remains an offence, with all the consequences that implies.

For the future, we can expect greater specialisation of judges. Some courts are already creating specialised divisions in planning law, with magistrates specifically trained in these matters. An evolution that should allow for faster and better-adapted procedures.

Key points to remember

• The investigating judge can investigate planning offences: this is the common law rule, confirmed by the Court of Cassation.
• Sanctions are heavy: up to €300,000 fine and 6 months' imprisonment, in addition to administrative fines.
• The procedure can be lengthy: budget 1 to 3 years before the investigating judge, compared to 6 to 12 months in simplified procedure.
• Prevention is crucial: a building permit costs less than a fine, and much less than a judicial procedure.
• Consult before acting: a specialised lawyer can save you many troubles, for a modest cost compared to the risks incurred.

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