Alcohol interlock in Belgium: when it is mandatory, what it costs and how to defend yourself

In Belgium, the alcohol interlock has become a standard tool of the police courts (politierechtbank / tribunal de police), including in Brussels, Halle, Vilvoorde, Leuven and Aalst. Anyone caught with a high level of alcohol intoxication rarely escapes it. Yet the measure is less automatic than it seems, and the way the hearing is prepared helps determine how heavy it turns out to be.

What is an alcohol interlock?

An alcohol interlock is a device fitted in the vehicle that only lets the engine start after you have taken a breath test showing no alcohol. Legally, the alcohol interlock is a restriction on the validity of your driving licence: you may only drive motor vehicles fitted with such a device. You must also follow a supervision programme (omkaderingsprogramma / programme d’encadrement) with an approved body (Article 37/1 § 1 read together with Article 61quinquies § 3 of the Road Traffic Act, Wegverkeerswet / loi relative à la police de la circulation routière).

When is an alcohol interlock possible, and when is it mandatory?

• Possible for any conviction for alcohol intoxication (Article 34 § 2), drunkenness (Article 35) or reoffending (Article 36), for a period of one to three years or permanently. In other words: in principle from 0.35 mg/l of exhaled alveolar air or 0.8 g/l of blood, and not only from 1.2 g/l, as is often assumed.
• Mandatory in principle where the breath analysis measures at least 0.78 mg/l, or the blood analysis at least 1.8 g/l. A judge who does not impose the measure in that case must give express reasons.
• Also mandatory in principle for reoffending within the meaning of Article 36 after a conviction under Article 34 § 2, with a lower threshold: each reading, i.e. for both offences, must be at least 0.50 mg/l, or 1.2 g/l.

This obligation does not apply where the judge imposes a permanent driving ban (verval van het recht tot sturen / déchéance du droit de conduire) or applies Article 42 (a ban for unfitness to drive). The limits that apply on the road are explained in our article on the drink-driving limit in Belgium.

How much does an alcohol interlock cost?

Installation, rental of the device, periodic checks and the supervision programme are at your own expense. As a guide, expect around 3,600 to 4,000 euros for an alcohol interlock programme, including installation (around 1,000 to 1,500 euros) and the monthly rental (around 100 to 150 euros). If the measure lasts longer, the rental keeps adding up.

There is, however, an important counterweight: the judge can reduce the fine by the costs of the alcohol interlock and the supervision programme, down to a minimum of one euro (Article 37/1 § 3). This does not happen automatically: you have to ask for it, with an estimate of the costs. Your financial means are also taken into account when the fine is set (Article 52 § 2 of the Criminal Code).

Alcohol interlock or driving ban?

If you depend on your car for work, an alcohol interlock is often more bearable than a long, effective driving ban: you keep driving. Against that stand the cost and the mandatory supervision.

It is best to weigh this up before the hearing, because it determines which penalty you yourself propose to the court. In many cases, the strongest position is not “no alcohol interlock” but a clearly substantiated proposal: a limited duration, combined with a reduced fine and an excluded vehicle category. How the driving ban itself works is explained in our article on the driving ban.

Can the alcohol interlock be limited to certain vehicles?

Yes. The judge may, giving reasons, designate one or more vehicle categories to which the restriction does not apply (Article 37/1 § 2). The restriction must, however, always cover at least the category of vehicle with which the offence was committed. For professional drivers, this is sometimes the solution that saves their job.

And what if I don’t have the interlock installed?

Then you may not drive. Anyone who nevertheless drives a vehicle without the alcohol interlock imposed commits a separate offence (Article 37/1 § 4 of the Road Traffic Act). The same applies to anyone who, as a driver, fails to comply with the conditions of the supervision programme. For offences committed on or after 1 September 2026, this is a level 2 offence under the new Criminal Code, with a fine of 5,000 to 20,000 euros (surcharge decimes included, known as opdeciemen / décimes additionnels). The court must also impose a new driving ban lasting at least as long as the period during which your licence was restricted.

Level 2 allows, among other options, imprisonment of six months to three years or community service. For offences committed before 1 September 2026, the penalty in force at that time continues to apply, unless the new rules are more favourable (Article 2 of the Criminal Code).

What else do you risk besides the alcohol interlock?

The alcohol interlock comes on top of the penalty for the alcohol offence itself. For offences committed on or after 1 September 2026, the following applies (surcharge decimes included):

• Alcohol intoxication from 0.35 mg/l (Article 34 § 2): level 1, with a fine of 2,000 to 20,000 euros. Imprisonment is not possible at this level.
• Drunkenness (Article 35): level 1, with a fine of 2,000 to 20,000 euros and a mandatory driving ban of at least one month.
• Reoffending within three years (Article 36): level 2, with a fine of 4,000 to 50,000 euros. A further repeat offence may lead to level 3, with a fine of 8,000 to 100,000 euros.

For older offences, the previous rules still apply: for alcohol intoxication, 1,600 to 16,000 euros (offences before 1 February 2026) or 2,000 to 20,000 euros (offences between 1 February and 31 August 2026). Read more in our article on the new Criminal Code and road traffic and on our page drink-driving: penalties and driving bans.

Our lines of defence

• Below 1.8 g/l, without reoffending: showing, with reasons, why a standard driving ban is enough: a one-off incident, a clean criminal record, the professional context, support already completed.
• From 1.8 g/l: giving the judge the reasoning that allows a lawful departure. The law requires express reasons, not impossibility.
• If the interlock is unavoidable: limiting the duration to the legal minimum, arguing for the fine reduction and having the vehicle categories defined.
• Always: first checking whether the measurement itself holds up (device, calibration, how the breath analysis was carried out). An irregular analysis may lose its evidential value, and with it the basis for an alcohol interlock.

Where the case allows it, we also ask for a suspension of the pronouncement (opschorting / suspension du prononcé), a suspended sentence (uitstel / sursis) or community service. Read more about suspension, suspended sentences and community service before the police court.

Novex Advocaten can help

If an alcohol interlock is looming in your case, get in touch before the hearing: the arguments the judge needs in order to depart from it must be on the table at that point. Send us the summons (dagvaarding / citation) and, if you have them, the documents relating to the breath analysis.

Mr Mohamed Asfour, lawyer, appears before the police courts of Brussels, Halle, Vilvoorde, Leuven and Aalst. You can read more about our approach on the page drink-driving lawyer.

Call 0484 99 22 72 or email asfour@novexadvocaten.be.