​Washington state’s marijuana legalization Initiative 502 has plenty of prominent backers and a healthy war chest of money heading towards the November election. So why do many of the state’s most prominent cannabis advocates oppose it?

One of the most troublesome reasons, according to Patients Against I-502, is its faulty DUI provision which would create a per se DUI charge for anyone testing over the low, arbitrary and scientifically unsupported blood THC level of of five nanograms per milliliter (5 ng/ml).