Construction Without a Permit and Non Bis in Idem: Is a Double Conviction Possible?

You have undertaken works at your home, in Liévin, without meaning any harm. An extension of 20 m², some interior modifications… And now the administration notifies you of a report for construction without a building permit. You risk a fine, or even demolition. But that's not all: you are also accused of having violated the Plan d'Occupation des Sols (POS, the former name of the Local Urban Plan). Two offences for the same works? Is this not contrary to the principle "non bis in idem" (not twice for the same thing)?

This is precisely the question that the Court of Cassation decided in its judgment of 8 December 2015. A property owner had carried out works without a permit and in breach of the POS. Prosecuted for both offences, he invoked the principle that one cannot be punished twice for the same facts. But the high court validated the double conviction, on the grounds that these two texts protect legally distinct interests: one controls the granting of planning permissions, the other ensures the conformity of constructions with local planning rules.

What does this judgment mean concretely for you, a property owner in Lens or elsewhere? That you can be convicted for two offences at the same time, but only one penalty will be imposed. No double penalty, therefore, but a cumulation of charges that reinforces the repression of illegal constructions. Analysis of a decision that distinguishes between the rules.

The Facts: A Story Like Many Others That Happen Every Day

Mr X, owner of a house in Liévin, decides in 2010 to carry out works to extend and modify his facade. He thinks he is in order, but he did not apply for a modified building permit even though the works exceed the regulatory thresholds. Worse, these works do not comply with the prescriptions of the municipality's Land Occupation Plan. The municipal planning department notes the infringements and draws up a report.

Mr X is then prosecuted before the criminal court of Béthune for two offences: construction without a building permit (in violation of Articles L. 421-1 et seq. of the Planning Code) and violation of the POS (non-compliance with height, siting, etc. rules). He admits the facts but contests the cumulation of proceedings: according to him, these are the same works, so he cannot be convicted twice.

The court sentences him to a single fine of €10,000 for both offences. Mr X appeals, arguing a violation of the non bis in idem principle. The Douai Court of Appeal upholds the conviction, but clarifies that the two offences are distinct. Mr X appeals to the Court of Cassation. The Court of Cassation dismisses his appeal on 8 December 2015, thereby endorsing the possibility of cumulating charges, provided that only one penalty is imposed.

The Reasoning of the Court — Explained

The Court of Cassation first recalls the non bis in idem principle, derived from Article 4 of Protocol No. 7 to the European Convention on Human Rights (which prohibits judging or punishing a person twice for the same facts). But this principle is not absolute: it admits exceptions when the offences protect different legal interests.

In this case, the Court clearly distinguishes two objectives. On the one hand, the rules relating to the building permit (Articles L. 421-1, R. 421-1, R. 421-14 of the Planning Code) aim to control the granting of prior authorisations for any construction. On the other hand, the rules of the POS (now PLU) are intended to ensure that constructions comply with local planning guidelines and easements. These two sets of rules do not pursue the same purpose: one is procedural, the other is substantive.

The Court also relies on the fact that the lower courts examined in detail the content of the initial building permit, the nature of the works carried out, and found that Mr X should have filed an application for a modified permit. They also noted that the authority granting the permit checks its compliance with the POS, but that this prior check does not prevent separately sanctioning the violation of the POS if it occurs. Thus, the cumulation of charges is possible provided that only one penalty is imposed, which was the case here with a single fine of €10,000.

This judgment is a confirmation of prior case law (Crim., 12 March 2013, No. 12-80.033) and not a reversal. It is part of a trend towards increased severity against illegal constructions.

What This Changes for You — Concretely

If you are a property owner and you carry out works without a permit or in breach of the PLU, you can be prosecuted for two distinct offences. However, you will only be sentenced to one penalty. This means that the criminal risk remains limited to a fine, but the amount may be higher because the judge takes into account the double charge.

Let's take an example: in Lens, a property owner builds a 30 m² conservatory without a permit and without respecting the height rules. He risks a fine of €1,200 to €300,000 (Article L. 480-4 of the Planning Code). If both offences are retained, the judge can set a single fine closer to the maximum. In practice, the courts of Béthune or Douai often impose fines of €5,000 to €20,000 for similar cases.

For a tenant who carries out unauthorised works, the risk is twofold: he can be criminally prosecuted and have his lease terminated for failure to maintain or unauthorised modification. As for co-owners, beware: works modifying common parts without the authorisation of the general meeting can lead to both a criminal penalty and a civil action for restoration.

If you are in this situation, you should immediately consult a lawyer specialised in property law to assess the risks and prepare your defence. A posteriori regularisation is sometimes possible, but it does not erase the offence.

Four Tips to Avoid This Type of Dispute

• Always check whether your works require a building permit or a prior declaration. Before starting, consult the service-public.fr website or go to the planning department of your town hall. The thresholds are strict: beyond 20 m² of floor area, a permit is generally required.
• Comply with the rules of your municipality's PLU (Local Urban Plan). Each municipality has its own rules on height, siting, external appearance. Consult the PLU at the town hall or online to avoid unpleasant surprises.
• If in doubt, request an operational planning certificate (CU). This document tells you whether your project is feasible and under what conditions. It protects you in the event of a subsequent inspection.
• If you make changes during construction, submit a modified permit. If your initial project is regular but you change your mind, do not delay in regularising. The absence of a modified permit is an offence in itself.

Further Analysis: Related Case Law and Developments

The Court of Cassation had already admitted the cumulation of charges for planning offences in a judgment of 12 March 2013 (No. 12-80.033). In that case, a developer had built without a permit and in violation of the POS. The Court held that the two offences were distinct and could be retained together. The 2015 decision confirms this position and clarifies it by emphasising the condition of a single penalty.

Since then, the trend has been towards strengthening the repression of illegal constructions. The ALUR law of 24 March 2014 increased the powers of mayors and the penalties. Courts no longer hesitate to order the demolition of unauthorised constructions, even in the absence of a permit. For the future, expect increasingly strict enforcement: the cumulation of charges could become the norm, especially in high-pressure areas like the Nord mining basin.

Frequently Asked Questions

• Can I be sentenced to two different penalties for the same works? No, the Court of Cassation requires a single penalty in case of cumulation of charges for identical facts.
• What should I do if I receive a report for construction without a permit? Consult a lawyer immediately. You can try to regularise by submitting a building permit a posteriori, but this does not guarantee the extinction of proceedings.
• What is the maximum fine for construction without a permit? Up to €300,000 (Article L. 480-4 of the Planning Code), and the judge can also order demolition under penalty.
• Does the non bis in idem principle apply in planning matters? Yes, but it does not prohibit the cumulation of charges if the offences protect distinct interests, as here the control of authorisations and compliance with planning rules.
• Can I contest a conviction for violation of the POS if I have a building permit? Yes, but the permit does not exempt you from complying with the POS. If the permit was granted in violation of the POS, it can be annulled, and you will then be in breach.

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 →