Cannabis and driving in Switzerland – the complete guide

The traffic medicine assessment and the withdrawal of the driving licence

Following a detection of THC in the blood above the legal limit, the authorities initiate an administrative procedure. The competent road traffic office usually orders a traffic medicine assessment if there is suspicion of cannabis dependence or abusive consumption. Until the fitness to drive is clarified, the driving licence is provisionally withdrawn. Within the scope of this procedure, those affected must prove that they can reliably separate consumption and road traffic or maintain a phase of abstinence.

The traffic medicine examination is conducted by accredited specialists and includes physical assessments as well as traffic psychology interviews. A central element is the proof of abstinence over an extended period, which must be provided through regular urine or hair analyses. Only when the medical report provides a positive prognosis can the road traffic office reinstate the driving licence under certain conditions. This process involves significant costs and administrative effort for those affected.

CBD consumption and the pitfall of the limit value in road traffic

Although CBD products with a total THC content of less than one percent may be legally purchased and consumed in Switzerland, they pose a significant risk for drivers. Even legal CBD flowers or CBD oils contain minor traces of THC. With regular or intensive consumption, this THC accumulates in the body. This can lead to the strict limit value in the blood being exceeded during a police check, even though no psychoactive effect was noticeable.

When assessing driving ability, Swiss legislation does not distinguish between the consumption of illegal THC cannabis and legal CBD products. The only decisive factor is the analytically proven value in the blood. Since the breakdown of THC varies greatly from person to person, consumers of CBD products should, as a precaution, refrain from driving vehicles after consumption in order to consistently avoid criminal and administrative consequences in road traffic.

Medical cannabis in road traffic – The legal situation

Since August 2022, the prescription of medical cannabis in Switzerland has been possible without an exceptional licence from the Federal Office of Public Health. However, this facilitation in the medical field does not mean an automatic exemption from the strict rules of the Road Traffic Act. Patients treated with medicinal products containing THC are generally subject to the same legal provisions and limit values as all other road users, which leads to major challenges in everyday life.

For patients fit to drive, close consultation with the treating physician is essential. They must individually assess and document in writing the fitness to drive under the specific medication. A medical certificate can serve as a guide during a police check, but does not exempt the authorities from the obligation to order a blood sample if there is a reasonable suspicion of incapacity to drive. The final decision always rests with the road traffic authorities.

The specific procedure of a traffic control under suspicion of THC

During a police traffic control in Switzerland, the primary focus is on determining the current fitness to drive. In the event of a reasonable suspicion of narcotics consumption, the police may carry out rapid tests such as saliva or urine tests. These preliminary tests serve as circumstantial evidence and are not legally binding for those affected, but they can substantiate the suspicion. If the rapid test shows a positive result or if there are clear signs of impairment, the police will order a blood sample to be taken. This medical measure is carried out in a hospital and is decisive for the subsequent legal assessment, as only the blood values are considered legally admissible evidence in court.

During the check, officers document the driver's behaviour, pupil response, and motor skills. While cooperative behaviour does not protect against the legal consequences of a positive blood test, it does prevent additional complications. The blood sample is then analysed in a specialised laboratory to determine the exact level of active THC. Since the limit of 1.5 micrograms per litre of blood is set extremely low, almost any recent consumption leads to a positive result, which triggers administrative proceedings.

Cantonal differences in enforcement and the role of fixed penalty fines

The enforcement of legal requirements regarding cannabis possession and consumption in road traffic shows significant cantonal differences in Switzerland. While the mere consumption of cannabis with a THC content of over one percent by adults can be punished with a fixed penalty fine of 100 francs, provided the quantity is under ten grams, the stricter federal rules apply immediately in road traffic. The cantons use their federalist leeway regarding the intensity of checks and administrative processing. Some cantons systematically carry out large-scale traffic checks with drug tests, while others primarily test in the event of conspicuous driving behaviour or accidents.

This varying approach means that the risk of a check varies greatly depending on the region. Regardless of the canton, however, the legal zero-tolerance practice in road traffic remains uniformly regulated nationwide. As soon as the limit in the blood is exceeded, there is no longer any cantonal discretion. The road traffic office of the canton of residence takes over the administrative proceedings and orders the appropriate measures, such as the revocation of the driving licence or a traffic medical examination, whereby processing fees and waiting times here too depend heavily on the cantonal authority.

Pilot trials and the legal framework for participants

Scientific pilot trials with cannabis under Article 8b of the Narcotics Act are currently underway in various Swiss cities, such as Züri Can or Weed Care in Basel. These projects, approved by the Federal Office of Public Health, allow the regulated purchase of THC-containing cannabis for scientific purposes. However, participants in these studies do not enjoy any special rights or privileges in road traffic. Even those who consume legally acquired cannabis within the framework of a government-approved project must strictly adhere to the applicable limit values of the Road Traffic Act and expect the same consequences.

The study management regularly reminds participants that participation in the pilot trials is not a free pass to drive vehicles under the influence of drugs. Since the limit value of 1.5 micrograms of THC per litre of blood is extremely low, consumers must maintain a strict separation between consumption and participation in road traffic here as well. The scientific monitoring of the trials also examines, among other things, the mobility behaviour of the participants in order to gain new insights into the responsible use of cannabis in everyday life, without, however, compromising road safety.

Insurance law consequences and recourse claims

In addition to criminal fines and the administrative withdrawal of the driving licence, driving under the influence of cannabis carries the risk of serious financial consequences from insurance companies. Under Swiss insurance law, driving under the influence of substances that impair driving ability is considered gross negligence. If a driver with a THC level above the legal limit causes a traffic accident, liability insurance companies are legally obliged to take recourse against the person who caused the accident. This means that the insurance company can reclaim the benefits paid for personal injury and property damage in part or in full.

In the event of serious accidents involving personal injury, these recourse claims can quickly amount to life-threatening sums. In addition, comprehensive insurance policies generally completely exclude coverage for first-party damage when driving under the influence of drugs. The financial burden of compensation, coupled with the costs of traffic medical assessments, laboratory analyses, and court fees, usually exceeds the criminal fine many times over. Drivers should be aware that consuming cannabis in road traffic endangers not only their driving licence but also their financial existence.

How long is THC detectable in the blood after consumption?

The detection window of THC in the blood depends heavily on the frequency of consumption. In the case of one-off consumption, the concentration usually drops below the limit of 1.5 micrograms per litre of blood within a few hours. With regular consumption, however, THC accumulates in the fatty tissue and is only released slowly. As a result, the limit can be exceeded even days or weeks after the last consumption, leading to unfitness to drive.

What happens if I refuse a drug test during a police check?

Refusing a rapid saliva or urine test on-site is legally permissible, but in practice almost always leads to a blood sample being ordered by the competent public prosecutor's office. The drawing of blood at the hospital is an official measure that cannot be refused. Furthermore, uncooperative behaviour during a check can strengthen the suspicion of unfitness to drive and accelerate the proceedings for the person concerned.

Are there exceptions to the THC limit for patients with a prescription?

No, in Switzerland there is no general exception to the limit of 1.5 micrograms of THC per litre of blood for medical patients. Even though medical cannabis has been regularly prescribable since August 2022, the zero-tolerance practice in road traffic remains in place. Those affected must, in consultation with their doctor, have their fitness to drive individually assessed under the medication and determine how the risk can be minimised.

What costs can I expect for a traffic medicine assessment in Switzerland?

The costs for a traffic medicine assessment in Switzerland must be borne by the individuals concerned and usually amount to several thousand francs. This amount is made up of the fees for the accredited specialists, the fees of the Road Traffic Office, and the costs for the necessary laboratory analyses such as urine or hair screenings. Since the tariffs vary by canton and depending on the effort involved, those affected should obtain information from the responsible authority at an early stage.

Can my driving licence also be revoked if I only consume cannabis as a passenger?

No, as a mere passenger, you do not normally face a revocation of your driving licence, as long as you are not actively driving the vehicle. However, during a check, the police can record your personal details if there is a suspicion of illegal possession of cannabis. Should the authorities thereby obtain indications of a general cannabis addiction that fundamentally calls your fitness to drive into question, the Road Traffic Office can theoretically order an assessment even without a direct journey.

How should I behave correctly if the police demand a drug test?

During a police check, you should remain calm and cooperative to avoid unnecessarily escalating the situation. You have the right to refuse voluntary rapid tests on site, but you must know that in the event of reasonable suspicion, this almost always leads to an officially ordered blood test. You must comply with this blood sample collection at the hospital, as a refusal is deemed to be an evasion of measures to determine unfitness to drive.

Does the zero-tolerance limit of 1.5 µg/L also apply to e-scooters and bicycles in Switzerland?

Yes, the strict rules on unfitness to drive and the corresponding limit values fundamentally apply to all vehicle drivers in Switzerland, including e-scooter and bicycle riders. Anyone who drives such a vehicle under the influence of THC not only endangers themselves but is also liable to prosecution. Depending on the type of vehicle, a check can result in fines, driving bans for certain vehicle categories and, in the worst case, also the revocation of the car driving licence.