"Impaired" is a medical condition, not some arbitrary number. You can be impaired by alcohol or drugs, or you can be impaired due to lack of sleep or a mental or physical disability, or even age. It's how the impairment affects your ability to drive that should be the focus. An all-day every-day smoker like myself won't feel or display the same impairment as a occasional toker at the same level of thc. If the spirit of the law is to keep our roads safe, they need to shift their focus from worrying about how much of whatever substance we have in our bodies and target dangerous and aggressive drivers that are causing the accidents. Any stats out there on how many accidents are caused by someone using cannabis vs. those caused by age (young and old), or even prescription drugs? This is just a witch hunt to continue the demonetization of cannabis. Some neanderthals just can't wrap their heads around 21'st century thinking. They lost the war on pot and are just taking a few parting shots.