Eric Levitz at MSNBC:

The United States has a problem with painkillers. During the past 15 years, America has seen a tremendous growth in both the sales of prescription opiates and the number of people who die each year from abusing them. More than 16,000 people fatally overdosed on prescription painkillers in 2013, accounting for 60% of all overdose deaths, according to the Center for Disease Control. But a new study suggests that some states have already stumbled onto a means of curbing this fatal epidemic: Easily-accessible marijuana.