My bullshit detector went off when the article said "the number of drivers involved in fatal crashes who tested positive for marijuana is up significantly" (a reference to Colorado). Duh, the overall percentage of the population smoking dope went up when legalized.

Cannabis detection devices in Australia (NSW anyway, maybe VIC and other states) seem to have a detection window of a couple of days or more. So it's almost entirely moral policing operational over here. This would be an improvement on that.