In short
Under § 13a FeV, you usually only need an MPU because of cannabis if you have driven under the influence of cannabis repeatedly, in practice mostly from the 2nd drive above 3.5 ng/ml THC. It can be ordered after the first drive if there are additional facts such as very high values, mixed use or signs of dependence.
What has changed for the cannabis MPU since 2024?
Since 2024, the cannabis MPU (medical-psychological assessment, Medizinisch-Psychologische Untersuchung) has had its own legal basis: § 13a FeV (Driving Licence Regulation, Fahrerlaubnis-Verordnung). With the legalisation of cannabis, cannabis was taken out of the general drug rules and a provision was created that is modelled on § 13 FeV for alcohol.
At the same time, the THC limit in road traffic was raised. Since 2024, under § 24a StVG (Road Traffic Act, Straßenverkehrsgesetz), a limit of 3.5 ng/ml THC in blood serum has applied; previously it was 1.0 ng/ml. Anyone who drives above this limit commits an administrative offence (Ordnungswidrigkeit).
The most important change for you: occasional cannabis use no longer automatically calls your fitness to drive into question. What matters is whether you separate consumption and driving and whether there are indications of an entrenched problem. The guide Cannabis legalisation and your driving licence shows all the changes in detail.
| Topic | Before legalisation | Since 2024 (as of 2026) |
|---|---|---|
| Legal basis of the MPU | General drug rule (§ 14 FeV) | Separate rule: § 13a FeV |
| THC limit in traffic | 1.0 ng/ml blood serum | 3.5 ng/ml blood serum (§ 24a StVG) |
| Occasional use | Could already raise doubts about fitness | No longer automatically calls fitness into question |
| MPU after driving under cannabis | Under the general drug rules | For "repeated" offences, in practice mostly from the 2nd drive |
| Dependence | Fitness ruled out | Fitness ruled out until 1 year of proven abstinence |
Note: The legal position on cannabis is still evolving. The assessment criteria (Beurteilungskriterien) were only adapted to the Cannabis Act in the 5th edition in 2026. In addition, the interpretation of "repeated" is based on authority practice, not on a fixed number in the law.
When may an MPU be ordered because of cannabis?
Under § 13a FeV, an MPU because of cannabis is likely above all in the case of repeated offences in road traffic under the influence of cannabis. The law deliberately gives no fixed number for this.
A rule of thumb has therefore become established in authority practice: from the 2nd drive above the limit, the MPU is ordered as a rule. The often-quoted rule that a first drive is "free", however, is only common practice and is not written in the law.
Besides driving under the influence of cannabis, suspected misuse or dependence can also trigger an order. What is binding is always what is stated in the order from your driving licence authority (Fahrerlaubnisbehörde). You can find a general overview of all reasons under Do I need an MPU?.
When is the first cannabis drive enough for an MPU?
Even the first cannabis drive can be enough for an MPU if there are additional facts (Zusatztatsachen) that indicate a deeper problem. The authority then does not wait for a second incident.
Typical additional facts are:
- Very high acute THC value: for example more than 11 ng/ml THC in blood serum.
- High THC-COOH value: more than 150 ng/ml THC-COOH. This breakdown product indicates regular use.
- Mixed use: cannabis together with alcohol or other substances.
- Signs of dependence: for example from medical findings or the circumstances of the check.
| Situation | Typical consequence (guideline, as of 2026) |
|---|---|
| 1st drive just above 3.5 ng/ml, no additional facts | Administrative offence, usually no MPU yet |
| 1st drive with more than 11 ng/ml THC or more than 150 ng/ml THC-COOH | MPU possible |
| 1st drive with mixed use or signs of dependence | MPU possible |
| 2nd drive above 3.5 ng/ml | MPU is ordered as a rule |
| Established dependence | Fitness only after 1 year of proven abstinence |
What applies in the case of cannabis dependence?
If you are dependent on cannabis, your fitness to drive is ruled out until you can show 1 year of proven abstinence. § 13a FeV and the assessment criteria are in agreement on this.
The proof must follow the CTU criteria: with an accredited laboratory, unannounced appointments and complete documentation. Urine tests or hair analyses are possible. A positive result or a missed appointment usually invalidates the current programme. The page Proof of abstinence explains how this works in detail.
Even without dependence, the authority or the assessor can demand proof. Which period makes sense in your case depends on your values and your history. So only start a programme after file inspection (Akteneinsicht), but then without delay.
Am I allowed to drive with medical cannabis?
With medical cannabis on prescription, you are in principle allowed to drive, because the medication privilege under § 24a (4) StVG (Medikamentenprivileg nach § 24a Abs. 4 StVG) applies. The administrative offence from 3.5 ng/ml does not apply as long as you take the medicine as intended.
As intended means: there is a clear medical prescription with a clear dosage, and you stick to it. Misuse or overdosing are not covered.
The privilege has clear limits. It does not protect you if you are unfit to drive, i.e. if there are signs of impairment or an accident. You then face a penalty and doubts about your fitness to drive. Mixed use with alcohol or other substances also speaks against fitness. For health-related questions about fitness to drive, the page Medical MPU will help you.
How does an MPU because of cannabis work?
Like every MPU, an MPU because of cannabis consists of a questionnaire, a medical examination, a performance test and a psychological interview. In total, it takes about 3 to 4 hours.
The psychological interview is about your consumption and your behaviour in road traffic:
- How did your consumption develop, how often and in what situations did you use cannabis?
- Why did you drive despite having used cannabis, and what was the real reason?
- What has specifically changed since then, and how do you prove it?
- How will you deal in future with situations in which consumption and driving could come together?
The assessor compares your statements with the values in your file. An account that does not match high THC or THC-COOH values stands out. Anyone who has used other substances in addition to cannabis should read the page MPU because of drugs, because stricter rules apply there.
For drug-related questions, the fee for the expert report (Gutachten) is around €550 to €750 (guideline 2026), plus proofs of abstinence and preparation if applicable.
What happens next?
Apply for file inspection and check which values and which question the authority states. Because the legal position on cannabis is still evolving, a lawyer specialising in traffic law (Fachanwalt für Verkehrsrecht) can be helpful if you have doubts about the order. For preparing the content, you can find suitable counselling through MPU Plus.
Frequently asked questions
How many ng of THC are allowed when driving?
Since 2024, a limit of 3.5 ng/ml THC in blood serum has applied under § 24a StVG. Anyone who drives above it commits an administrative offence. Whether an MPU is also likely depends on repetition and additional facts.
Will I get an MPU after my first cannabis drive?
Usually not, if it remains a value just above 3.5 ng/ml without any other issues. It is different if there are additional facts such as more than 11 ng/ml THC, more than 150 ng/ml THC-COOH, mixed use or signs of dependence. Then even the first drive can lead to an MPU.
Is there a "two drives free" rule for cannabis?
No, not in the law. § 13a FeV only refers to repeated offences without a fixed number. The fact that the MPU is usually ordered from the second drive is common authority practice.
Does a cannabis prescription protect me from the MPU?
A prescription protects you from the administrative offence if you take medical cannabis as intended. However, if there are signs of impairment, an accident, overdosing or mixed use, the medication privilege under § 24a (4) StVG does not apply. You then face a penalty and doubts about your fitness to drive.
How long do I have to be abstinent in the case of cannabis dependence?
If cannabis dependence has been established, fitness to drive is only considered possible again after 1 year of proven abstinence. The proof must be provided through a recognised programme in line with the CTU criteria.