Medical driving fitness assessment

Who orders the assessment?

The cantonal traffic office orders the assessment – usually after a positive test with high THC-COOH values, repeated flags or a police/medical report. The driver picks a certified Level-3 traffic-medicine physician (SGRM).

How to pass the assessment

• Documented abstinence via repeated urine/hair analyses over 6–12 months.
• Evidence of strict separation between use and driving.
• No parallel use of alcohol or other substances during the review window.
• Honest, consistent narrative of one's own use history in the interview.

Swiss practice: procedure, deadlines and costs

A traffic-medicine assessment (fitness-to-drive evaluation) is ordered when basic fitness is in doubt — typically after repeat incidents, very high THC values or signs of regular use. It is carried out by level-4 certified traffic physicians, usually at a forensic medicine institute. The process covers a detailed history interview, a physical examination and an abstinence programme with hair analyses (usually six months, three-month segments) or close-interval urine checks. Costs fall on the person concerned: typically CHF 1,000–2,500 for the report plus CHF 200–400 per hair analysis. Important: CBD use can also produce THC findings in hair, since legal CBD flower may contain up to 1 % THC — anyone in an abstinence programme should therefore also avoid smokable CBD products.

Differentiation between driving competence and fitness to drive

In Swiss road traffic law, a strict distinction is made between acute driving competence and basic fitness to drive. While driving competence describes the practical and theoretical skills to drive a vehicle safely, fitness to drive encompasses the physical and psychological condition of a person in the long term. A cannabis offence usually raises doubts about fitness to drive among the authorities. It is assumed that there is regular consumption that impairs long-term reliability in road traffic. The traffic medical assessment serves exclusively to evaluate this character and medical fitness by means of an expert opinion, regardless of the affected person's current driving skills.

The assessment therefore does not focus on a one-off lapse of attention, but on the deeper consumption habits and personality structure. In the event of suspected substance dependence or regular abuse, the Road Traffic Office proceeds in accordance with the guidelines of the Ordinance on the Admission of Persons and Vehicles to Road Traffic (VZV). Only when the fitness to drive has been restored by a positive expert assessment may the person concerned participate in traffic again. The distinction is essential for those affected, as a passed driving test or decades of accident-free driving experience have no legal relevance whatsoever if there are doubts about the fitness to drive, and cannot shorten the procedure.

The problem of CBD consumption during the abstinence phase

A common stumbling block in traffic medicine assessments in Switzerland is the consumption of supposedly harmless CBD products. Since the Swiss legislator has set a limit of under 1 percent total THC for CBD flowers and corresponding products, these products are legally available. Many of those affected falsely assume that consumption during an ongoing abstinence programme will have no consequences. However, this is a grave misconception, as even the smallest amounts of THC accumulate in the body with regular consumption and can be detected in the hair or urine.

The analytical methods used in the laboratory are highly sensitive and do not differentiate in their limit values whether the detected THC originates from illegal cannabis or legal CBD products. Since a strict zero-tolerance policy with a limit value of 1.5 micrograms of THC per litre of blood applies to road traffic in Switzerland, any detection of THC metabolites in the proof of abstinence leads to the failure of the assessment. Anyone undergoing the procedure must therefore strictly avoid all CBD products in order not to jeopardise the success of the traffic medicine examination.

Cantonal differences in regulatory enforcement

Although the Road Traffic Act and the Ordinance on the Admission of Persons and Vehicles to Road Traffic are regulated at the federal level, the enforcement of traffic medical measures falls under the jurisdiction of the cantons. In practice, this leads to noticeable differences in the handling of cannabis offences. The cantonal road traffic offices enjoy a certain degree of discretion when it comes to ordering assessments. While some cantons immediately order a traffic medical examination even for minor first-time offences or low THC levels in the blood, other authorities take a more pragmatic approach and only require an expert assessment in the event of repeated incidents.

Processing times and administrative fees for the ruling on the provisional withdrawal of fitness to drive also vary considerably depending on the canton. In densely populated cantons with a high volume of cases, the procedure from the initial police check to the actual examination date can drag on for several months. This waiting period involuntarily extends the phase without a driving licence, as the withdrawal usually applies provisionally from the day of the incident. Those affected should therefore inform themselves early on about the specific procedures in their place of residence.

Typical mistakes in the psychological assessment interview

In addition to the purely medical laboratory findings, the psychological interview with the traffic medical expert represents the greatest hurdle in the assessment procedure. A common mistake is downplaying past consumption or attempting to deceive the authorities with implausible stories. Experienced assessors immediately recognize contradictions between the statements made during the interview and the biological measurements of the hair analysis. Such behavior is interpreted as a lack of insight and almost always leads to a negative assessment, as the character reliability required for participating in road traffic cannot be established.

Another mistake is the assumption that simply adhering to the abstinence period is sufficient for a positive result. The assessment requires a profound examination of the causes of past consumption and a stable change in behavior for the future. Anyone who merely states in the interview that they are stopping because of the threat of having their driving licence withdrawn shows no genuine awareness of the problem. What is required is a reflective attitude that explains why consumption has been permanently discontinued and how relapse situations in everyday life are to be actively avoided.

Can I lose my driving licence despite a medical prescription for medical cannabis?

Yes, the withdrawal of the driving licence is also possible with a legal medical prescription. Although medical cannabis has been prescribable in Switzerland without an FOPH exceptional licence since August 2022, this does not exempt patients from the obligation of fitness to drive. The strict detection limit of 1.5 micrograms of THC per litre of blood in road traffic still applies. In the event of justified doubts regarding reaction capacity or driving safety under medication, the road traffic office can order a traffic medicine assessment to review the individual fitness to drive in an expert opinion on a case-by-case basis.

What happens if a hair analysis cannot be carried out because the scalp hair is too short?

If the scalp hair is too short for an analysis, traffic medical examiners usually resort to body hair. For this purpose, chest, armpit or pubic hair can be used, for example, as these also accumulate substances. If no hair material is available at all due to a full-body shave, the abstinence programme is usually switched to closely monitored, unannounced urine tests. However, this significantly increases the organisational effort for the person concerned, as the sample must be provided under direct supervision and within very short deadlines after being requested.

Do different road traffic rules apply to participants in state-run cannabis pilot trials?

No, exactly the same legal provisions apply to participants in the official Swiss pilot trials as to all other road users. Although the time-limited projects such as Züri Can or Weed Care allow controlled purchase and consumption, they do not override the Road Traffic Act. Anyone caught behind the wheel with active substance concentrations above the legal limit of 1.5 micrograms of THC per litre of blood is deemed unfit to drive. Consequently, this also carries the risk of driving licence withdrawal and the ordering of a traffic medicine assessment.

Am I still allowed to drive a car while the assessment procedure is ongoing?

As a rule, driving motor vehicles is not permitted while the procedure is ongoing. The cantonal road traffic office usually withdraws the driving licence as a precautionary measure as soon as there are justified doubts about the fitness to drive and the assessment is ordered. This precautionary withdrawal remains in force until a legally binding, positive traffic medicine assessment is available, which confirms unrestricted fitness to drive. Anyone who drives a vehicle despite the precautionary withdrawal is liable to prosecution and risks a significant extension of the ban period as well as criminal consequences.

Frequently asked questions

Are hair analyses always required?

Not always, but often – they reveal use up to 6 months back and are hard to manipulate.

What does a traffic-medicine assessment cost in total?

Typically CHF 1,000–2,500 for the report plus CHF 200–400 per hair analysis over six to twelve months — all borne by the person concerned.