A new study produced by a Colorado researcher threatens to upset one of the supposed scientific certainties about impairment and blood-THC levels.

In the study, each subject tested positive for THC, but when comparing blood drawn from different parts of the body, researchers found dramatic disparities in THC levels. They also found disparities in THC levels drawn soon after death, compared to blood drawn hours or days later from the same subject.

See the original article at Leafly