Here you can find out what authorities and traffic experts recommend to ensure your ability to drive after consuming cannabis.
Since the legalization of cannabis on April 1st, there has been one central question: When will you be able to drive again after consumption? The new limit of 3.5 ng/ml THC in the blood serum is intended to provide clarity, but is still viewed critically by experts, as the ability to drive can still be impaired even at concentrations below this value.
Can drivers test themselves?
There are currently no reliable self-tests that drivers can use to determine the current THC level in their blood. The tests available for home use are mostly urine tests that only detect THC breakdown products. These tests are not suitable for assessing acute driving ability as they do not allow direct conclusions to be drawn about the current THC concentration in the blood.
For an exact measurement, a laboratory analysis is required, as is carried out in police blood tests. As long as there are no accessible and reliable rapid tests on the market, it will remain difficult for cannabis users to determine THC levels in the blood. Until then, personal responsibility remains the best protection – and the recommendation to avoid driving for at least 24 hours after consumption.
ADAC test: Restrictions even hours after consumption
A ADAC testing and the Bild newspaper illustrate the current problem. Three casual cannabis users were examined at a closed testing site. The experts checked their driving and cognitive abilities before and after consumption – one hour, four hours and 20 hours later – as well as the THC level in the blood. The results showed significant drops in performance immediately after consumption, with THC concentrations ranging between seven and twelve ng/ml.
Even four hours after consumption, when the THC levels had already fallen below the new limit of 3.5 ng/ml, it was found that the test subjects’ driving performance and cognitive performance remained impaired. Only after 20 hours did the test results return to the original values. The ADAC therefore recommends that you avoid driving for at least 24 hours after consumption, as the exact effect of the cannabis consumed is difficult to assess.
The BMDV about personal responsibility and rapid THC tests
The Federal Ministry for Digital and Transport (BMDV) emphasizes the personal responsibility of drivers. “Every motor vehicle driver must carefully check before setting off whether he can meet the requirements of road traffic,” the ministry said upon request. Cannabis users should be able to perceive the cannabis-related performance losses themselves and assess whether they are fit to drive. However, the breakdown of THC in the blood is not linear, as with alcohol, and regular users could still have high levels even after a long wait.
The ministry recommends a waiting period of at least 12, preferably 24 hours, to ensure that your ability to drive is no longer impaired. In addition, the Federal Highway Research Institute (BASt) was commissioned to examine the use of rapid THC tests, particularly for police traffic controls.
Conclusion
The new limit of 3.5 ng/ml THC in blood serum provides guidance, but the ADAC test shows that driving safety can be impaired even at lower THC concentrations. Self-tests are currently not a reliable option for checking your ability to drive. The responsible decision not to drive for a sufficient period of time after consumption therefore remains essential. Experts recommend a waiting time between 12 and 24 hours.
