The feds have an improbable scapegoat in their war on weed: Dr. Robert Mastroianni, a family physician in the Sierra foothills, who’s been practicing for 20 years. DEA agents opened a formal investigation of the California doc in January, after obtaining evidence that he’s recommended pot to three of his 6,000 patients since Prop 215 passed.

In December, the Bay Area Physicians for Human Rights filed a class-action lawsuit to prevent the feds from prosecuting doctors who prescribe pot. As the lead plaintiff, world-class AIDS researcher Dr. Marcus Conant loomed as a more likely target than nonactivist Mastroianni. According to an affidavit Mastroianni filed as evidence in the lawsuit, the narcs threatened arrest saying it was illegal to offer the “deadly” herb as therapy. “This was clearly meant to intimidate me and dissuade me from treating certain seriously ill patients. I am now reluctant to recommend…medical marijuana, even if it is my ethical duty to do so.”

Graham Boyd, the lawyer representing the doctors in the suit, said, “What happened to him shows that the government’s threats are not empty ones.”