Blood tests, unlike urinalysis, detect the presence of illicit drugs, not inactive drug metabolites. In general, THC only remains detectable in the blood of cannabis consumers for a few hours (though low, residual levels may be detected in chronic smokers for up to 12-24+ hours if more sensitive technology is used). Because of this narrow detection window, blood tests are typically only administered in the workplace post-accident in order to estimate recent cannabis consumption. Therefore, most after-hours consumers have little to fear from a blood screen.
Having a blood test to determine drug use is not [...]