I’m not saying this to say no accidents has been caused by cannibis, but that there’s currently no way to tell current level of cannabis intoxication. Authorities will use the lack of nuance in their favor.
No.
You are confusing the tests for cannabis metabolites (that can tell if you smoked weeks ago) to tests for THC, the substance that gets you stoned and leaves the bloodstream as you sober up.
A driving impairment test will test for THC, not metabolites. Nobody cares if you smoked last week, only if you are under the influence when driving.
In the UK, having 2ug / litre of THC in the blood is a drug-driving offence. At a minimum you will loose your licence for 1 year.
So I can have up to 8ug of THC in my blood? If I took 0.1mg (100ug) of THC (and would be very NOT high in this case, as it is 1/100th of a "normal" dose) I would probably be over the limit in that case, so sure they may be able to test for THC in the blood, but the limit is so laughably low as to effectively ban cannabis users from driving.
> Cannibis can be in your system for weeks or months
and the levels of active compounds[1] in somebody recently using, vs someone months away from use look very different, and their nature will generally work to the benefit of the defendant when reviewed by a competent forensic toxicologist.
[1] - not a yes/no from shitty screening methods; that kind of information comes off of quarter-million dollar mass spectrometers. they should be able to separate all of the inactive and active compounds from each other, enumerate them and list their exact concentrations in the blood.
Perhaps a car embedded in the second floor of a house?