Until recently, the law of the land firmly held that once the Food and Drug Administration approved a drug, doctors could prescribe it as they saw fit -- but the drugmakers could market the drug only for the FDA-approved indications as specified on the drug's so-called "label." Indeed, it was illegal for drug sales reps to even mention, let alone promote, the use of a drug for conditions that were "off label."

But Monday, a federal appeals court wrote a new script that could pose far-reaching side effects on U.S. drug regulation and patient safety. In a 2-1 decision, the judges of the 2nd U.S. Circuit Court of Appeals ruled that a pharmaceutical salesman's First Amendment rights of free speech had been violated when he was convicted in 2009 for promoting off-label drug use. His conviction was overturned, and the pharmaceutical industry celebrated.

As a doctor and a patient, I think this ruling was a big mistake. It jeopardizes drug regulation in the public interest, and it allows drug companies to have an even louder say in how medicine is practiced. It upholds and defends the free speech of a commercially motivated drug salesperson as though it were an abstraction, without considering the real risk of real harm to actual patients. But like yelling "fire" in a crowded theater, shouting out a drug's name in a busy clinic filled with harried physicians and vulnerable patients can cause mortal harm.

To underscore this point, it's instructive to revisit the government's evidence against Alfred Caronia -- the pharmaceutical salesman in the case. The allegations concerned Caronia speaking about Xyrem, a medication that had been narrowly approved by the FDA for particular subsets of patients with narcolepsy. Its active ingredient was GHB -- also known as "the date rape drug" -- and its known side effects included seizures, coma and death. The FDA had also required Xyrem to carry a black box warning that its safety and effectiveness had not been established for people under 16 years of age.

And yet ... taped conversations recorded by government investigators documented Caronia telling a doctor that Xyrem could be used for patients with rather common conditions: Parkinson's, fibromyalgia, excessive sleepiness, chronic fatigue, weight loss. (Translation: "for an enormous potential market."). Caronia also said that Xyrem could be used in patients younger than 16 years.

So the question becomes, how should we really judge Caronia's words? Should it matter if they persuaded doctors to prescribe Xyrem without -- or even against -- regulatory guidelines? Should we care whether real people, children included, were harmed by a potentially toxic drug that had never been proven effective as a treatment for their illness? Should we be asking how much it cost patients for Caronia's free speech?

I'm siding with patient safety in this case and aligning with the lone dissenting judge who argued that the majority decision called into question "the very foundations of our century-old system of drug regulation." She asserted that if drug companies "were allowed to promote FDA-approved drugs for nonapproved uses, they would have little incentive to seek FDA approval for those uses." Indeed, why waste time and money on safety and effectiveness research required by the FDA, if you can simply market a drug without it?

But I am also defending off-label prescribing when it is educated, fully informed, noncoerced and transparent to the patient. Those conditions are often difficult to achieve, because we doctors don't have access to a lot of unpublished drug data or unfavorable research studies that are hidden away in pharmaceutical company closets. Still, we try our best off-label strategies when our patients are suffering conditions for which no FDA-approved remedies exist. And never are those profoundly human and vexing conundrums made easier by drug salespeople whose self-interested free speech offerings are limited to positive drug spin.

Technically, the court's ruling applies only to those states located within the 2nd Circuit. But as a practical matter, its regulatory and legal reach could prove quite extensive. That's why I'm hoping that the FDA will swiftly appeal the decision.

In the meantime, let's remember this basic fact: That if the FDA hasn't approved a drug for use in your particular condition, that's because it's not been proven good for you to take that drug. You may still want to take it, you may still benefit from it, and your doctor may even recommend it to you. Regardless -- you with the illness, you bearing the risk of the drug's side effects, you opening your pocketbook to the pharmacy -- you should be entitled to know why the drug has not been approved for your condition, and what reasoning or whose theory supports you even trying it.

Kate Scannell is a Bay Area physician and syndicated columnist. Visit her website at www.katescannellmd.com.