A recent study examining the THC level of marijuana users found traces of the chemical about a month after their last use.
A sample of 30 heavy pot users found detectable levels in their blood of THC 29 days after following their last use of the drug. While the levels were undetectable in most after 30 days, one user had THC in his system 33 days into the study.
The study calls into question the DUI standards proposed for Washington state's initiative to legalize marijuana, initiative 502 or I-502. Under the proposed DUI law, drivers with 5 nanograms of THC per milliliter of blood would be declared driving under the influence. Critics of the proposed law, particularly medical dispensaries, claimed that the 5 nanogram rule would effectively turn all of their patients into criminals, even if they haven't smoked in days.
The study supports their position and is a rebuttal against a statement made by the National Organization for the Reform of Marijuana Laws' Executive Director Allen St. Pierre, who claimed that the medical marijuana industry was now driven by profits, not compassion.