I just read about it “am Rande” so take it with a grain of salt. Afaik, there is a legal limit for the blood traces, which is too low because the majority of people will not pass even several days after smoking. Said limit is therefore unrealistic and overly restrictive, they’re currently trying to figure out a number that makes more sense and still ensures that cannabis users are not a danger to themselves or anyone. Blood alcohol restrictions are a known quantity and have been for decades, but THC not so much so far.