THE OPIOID CRISIS, now the deadliest drug epidemic in American history, has evolved significantly over the course of the last two decades. What began as a sharp rise in prescription-drug overdoses has been eclipsed by a terrifying spike in deaths driven primarily by illicitly manufactured synthetic opioids and heroin, with overall opioid deaths climbing to 42,249 in 2016 from 33,091 in 2015. But prescription drugs and the marketing programs that fuel their sales remain an important contributor to the larger crisis. Heroin accounted for roughly 15,000 of the opioid deaths in 2016, for instance, but as many as four out of five heroin users started out by misusing prescription opioids. As the opioid epidemic worsens, many in the medical establishment are acknowedging that cannabis can play a role in reducing addiction.