Yes there is a direct correspondence to intoxication. I’m talking nanograms of THC which is present while a person is high (not THC-COOH). Testers could set a limit for THC based on actual impairment.
In 2007 a research team led by Franjo Grotenhermen at from the Nova Institute in Germany showed a THC level in blood of 10ng/ml was equivalent to the legal drink-driving limit of 0.05. (Gmel G, et al. BMC Public Health 2009;9(1):40.)
Setting a THC level that is based on evidence and comparable to alcohol impairment would be more widely accepted by drivers and smokers.
