By Nate Raymond (Reuters) – A federal appeals court on Thursday overturned key parts of the convictions of two Alabama doctors accused of running a massive “pill mill” after the U.S. Supreme Court in June made it harder to prosecute physicians for illegally prescribing addictive drugs like opioids. The Atlanta-based 11th U.S. Circuit Court of Appeals overturned the convictions of Xiulu Ruan and John Couch for unlawfully dispensing controlled substances after finding that under a Supreme Court ruling in June in Ruan’s case, jurors were wrongly instructed on how to determine their guilt. But the…