Doctors often prescribe drugs for off-label uses—and, if those drugs prove effective, doctors are more likely than not to share news of their success with their colleagues. But doing so can raise problems, as the current legal predicament of Alabama neurologist David R. Longmire dramatically illustrates.

Like many physicians treating epilepsy patients, Longmire first used the anticonvulsant Neurontin as a supplemental therapy to control seizures, for which it has FDA approval. In doing so, though, he observed an unexpected result: The patients he treated experienced a reduction in their accompanying pain. The idea that Neurontin could be used not simply to achieve better seizure control but also to reduce pain intrigued Longmire, who'd written several articles on the evaluation of certain forms of neuropathic pain.

After he began talking about his findings to colleagues, he received an invitation from Parke-Davis, the division of pharmaceutical maker Warner-Lambert responsible for the drug. The drug maker wanted him to participate in a meeting with other physicians who'd observed similar results. That meeting was the beginning of a series of efforts—by Longmire and others, who were paid by the drugmaker—to inform physicians about Neurontin's pain-relieving and other off-label effects.

The twin suits prompted Longmire to file one of his own. In May, he sued Warner-Lambert (along with Pfizer), for embroiling him in its fraudulent scheme. The suit sought damages both for the harm done to his reputation and the costs of defending himself in the other two cases. This summer, Warner-Lambert/Pfizer successfully filed a motion to dismiss the Longmire suit.

We looked through this thicket of actions and counteractions to see how a doctor who claims he acted in good faith went from sharing his off-label experiences with colleagues to his own legal hell.

A criminal case spawns a gaggle of civil suits

To understand Longmire's current legal mess, you need to go back several years, to the government's criminal indictment of Warner-Lambert. In that indictment, prosecutors charged the drugmaker with doing an end run around a key provision of the Federal Food, Drug, and Cosmetic Act. This provision says, in effect, that once the FDA approves a prescription drug for certain intended uses, the drug's maker can't market or promote it for other or "off-label" uses.

The prohibition doesn't extend to doctors, however. They can—and often do—talk to colleagues about their success with a particular drug's off-label use. Among other things, prosecutors charged Warner-Lambert with taking advantage of this fact, recruiting physician consultants to do something the company itself couldn't do: promote Neurontin for non-FDA-approved uses, including neuropathic pain control. Longmire was among the physicians who participated in these promotions, said prosecutors, although they stopped short of naming him as a defendant in their suit.

After the dust settled, Warner-Lambert pled guilty to two counts of violating the law and agreed to pay more than $430 million in fines and a settlement. Of this amount, $152 million went toward the settlement of claims at both the state and federal level, arising from Medicaid payments for Neurontin.

With the government's criminal and civil case resolved, private insurers across the country began taking aim at the drugmaker. Echoing many of the allegations set out in the government's case, they claimed in federal suit after federal suit that the pharmaceutical company's marketing practices had cost them money. (Now consolidated into two civil lawsuits, these cases are currently pending in federal district court in Boston.)