… In the consolidated cases of Ruan v. United States and Kahn v. United States, the Court delivered a 9-0 opinion, written by Justice Breyer, ... Drs. Ruan and Kahn were convicted under a provision of the Controlled Substances Act (codified at 21 U. S. C. §841) which makes it a federal crime to prescribe a controlled substance, “except as authorized.” A prescription is only authorized when it is a prescribed “for a legitimate medical purpose… acting in the usual course of his professional practice.” *** … Following his conviction, Dr. Ruan was sentenced to over 20 years in prison...