A federal appeals court has overturned the conviction of a drug rep for detailing a drug off-label on First Amendment grounds, ordering the lower court to retry the case.

The case, US vs. Alfred Caronia, has attracted interest in FDA law circles because some legal observers thought it had the potential to weaken the rules around off-label promotion. Today’s decision by the 2nd US Court of Appeals to vacate and remand the case back to the lower court for reconsideration suggests that might just happen—though it’s far from the final word.

“FDA is not going to roll over and play dead on this,” said John Kamp of the Coalition for Healthcare Communication, predicting a long slog through the courts. “It’s too important to them—it attacks the basis of most promotional regulation by FDA.”

In 2009, Caronia, a rep for Jazz Pharmaceuticals subsidiary Orphan Medical, was convicted of “conspiracy to introduce a misbranded drug into interstate commerce” for detailing the company’s CNS depressant Xyrem (AKA GHB), then indicated for cataplexy and since for narcolepsy, for insomnia, fibromyalgia, restless leg syndrome and other unapproved uses.

Circuit Judge Denny Chin wrote in today’s decision: “Caronia argues that he was convicted for his speech—for promoting an FDA-approved drug for off-label use—in violation of his right of free speech under the First Amendment. We agree.”

“What the court said was that there’s no question that the sole basis for prosecuting Mr. Caronia was what he said,” said Richard Samp, chief counsel of the Washington Legal Foundation, whose 1999 case against FDA, Washington Legal Foundation vs. Friedman, established that drug companies can distribute reprints of articles on off-label uses for their products, provided they appeared in peer-reviewed medical journals. “I don’t think this should be interpreted as overturning the FDA’s right to regulate in this area,” said Samp, “but they have continued to take the position that they’re regulating conduct, not speech, and they’ve lost that argument several times. I’m hoping with today’s decision they’ll recognize that.”

Industry legal sources note that there are similar cases wending their way through lower courts, and they hear echoes of the Supreme Court’s 2011 decision in IMS vs. Sorrell, in which the court ruled that Vermont could not ban the sale of prescription data to drug companies without violating First Amendment protections. Given this Supreme Court’s record of concern for commercial speech it seems likely the court will agree, should the case end up there.