Anyone who drives a motor vehicle with 3.5 nanograms of THC or more per millilitre of blood serum commits an administrative offence (§ 24a para. 1a StVG). Anyone who has also drunk alcohol falls under a separate, stricter rule (§ 24a para. 2a StVG). The measurement is taken in the blood, not in the urine. A saliva test during a check is only a preliminary test.
The value says nothing about how much someone has used or how long they have to wait. That depends on the amount, the THC content and habit. With regular use, the value can still be reached the next day.
During the probationary period and under 21, the rule at the wheel is: no THC at all. You may neither use while driving nor set off under the influence of THC (§ 24c StVG).
Regardless of the limit: anyone who cannot drive safely because of cannabis is committing a criminal offence, even below 3.5 ng/ml. Feeling sober is not a reliable measure.
Remember: If you have used cannabis, leave the car where it is until enough time has passed. The module explains the minimum waiting time.
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