southcitymom
Well-Known Member
Urinalysis for detecting marijuana use shows the presence of byproducts of THC. This can be detected for days to weeks after last use.
Blood tests for marijuana use show the presence of active THC rather than THC byproducts. In the first hour after using marijuana, the level of THC in one's bloodstream is very high. After one hour, the level drops dramatically and can remain for hours to a couple of days. A very high level of active THC in the blood is indicative of use within the hour and impairment in driving since this level drops to a very small amount after one hour.
I think it was a level of THC high enough to determine use within the hour that allowed them to make the determination that she was under the influence of marijuana at the time of the accident. It's not the presence of THC in the blood, but the level of THC that determines recent (within the hour) use and impairment.
Thank you very much for explaining that so clearly, Marina! That makes a lot of sense.