A benefit of federalism is that states can experiment with various ways to solve societal and legal problems. But this only works if states learn from one another. We recently recorded a webinar on how various states implement their DUI laws to deal with drugged driving. As part of that webinar, we revealed research results from Colorado demonstrating that a 5 ng/mL THC cannot discriminate between drivers who are and aren’t impaired, that such a law nearly guarantees that impaired drivers who test below the 5 ng/mL THC level will not be convicted under such a law, and that drivers who test below 5 ng/mL can indeed be impaired. Furthermore, Colorado data demonstrate that not only is a 5 ng/mL THC law ineffective, it is not even necessary to achieve a high conviction rate for drivers charged with driving under the influence of marijuana’s THC.