primary psychoactive compound in marijuana — and its inert metabolites (byproducts) is not a scientific or advisable approach to addressing traffic safety. Nonetheless, sixteen states now impose either ‘per se’ or zero tolerant ‘per se’ laws for motorists who operate a vehicle with even trace levels of these constituents in their blood or urine, regardless of whether or not they are behaviorally impaired. (Other states require evidence of recent drug use and evidence of behavioral impairment due to said use in order to go forward with a DUI drugs charge.) Additional states, like California, are proposing similar ‘per se’ laws for pot