By CARLA K. JOHNSON
A new study shoots down the notion that medical marijuana laws can prevent opioid overdose deaths, challenging a favorite talking point of legal pot advocates.
Researchers repeated an analysis that sparked excitement years ago. The previous work linked medical marijuana laws to slower than expected increases in state prescription opioid death rates from 1999 to 2010. The original authors speculated patients might be substituting marijuana for painkillers, but they warned against drawing conclusions.