One of the reasons Sean Benschop was arrested and charged was because he was allegedly operating a vehicle while impaired–there was marijuana detected in his blood stream, as well as unidentified painkillers. Thus far, most people, whether anecdotally or in the media, have focused on the question of marijuana rather than painkillers, although there’s a pretty good case to be made that the latter would impair functioning much more than the former.
Twenty years ago, the US Dept. of Transportation released a report saying that pot actually made drivers more cautious. That was a long time ago, but if the methodology is still considered sound, it’s an important factor. There are no prescription pain meds that don’t come with the warning about drowsiness and operating a motor vehicle. Seems we should be asking more questions about those.
But let’s get down to what the stoners in the audience really want to know: How long does pot stay in the system, anyway? The answer is, it depends. Here’s Nick Vadala on the subject:
If smoked, marijuana’s psychoactive effects tend to wear off in about two to four hours (about eight if eaten), but its byproducts remain in the body for hours or days afterward, especially in consistent, heavy smokers. Take, for example, the case of Denver Westword medical marijuana critic William Breathes, who took a blood test while unimpaired some 15 hours after last medicating. Breathes, who was declared sober by a doctor for the test, ended up with about 13.5ng/ml worth of THC in his body after 15 hours of abstention, nearly three times the legal amount proposed by Washington’s current I-502 marijuana legalization bill. In 2009, a similar study of 25 subjects found that six participants managed to test positive for THC after a week of abstaining from cannabis, the highest being 3 ng/ml.
Other say it can stay in the system for as long as a month, but that it’s different for different people. According to Christopher Morraff:
Unlike alcohol, there is no equivalent to the Breathalyzer to gauge pot intoxication, so investigators typically use a combination of observational data, intuition and, in many cases, a blood test to construct evidence that a suspect is high. But almost all experts agree that the results of these tests are inadequate for determining if a person was actually impaired at the time the blood was drawn.
This is all good news for Sean Benschop, whose lawyers will doubtless try to argue that science behind the testing is, as Morraff points out, “notoriously unreliable.”