Doctors aren't supposed to kill people. This basic medical precept has gotten renewed attention recently, as the public has become aware -- often through media coverage of court cases and legislative hearings -- of physicians' doubts about when and under what circumstances they may cease artificial life-support of dying patients without violating their medical oaths.

Judges and legislators -- as well as the general public -- have made it clear to physicians that it is not just medical ethics that forbids their taking human life. Criminal prosecution for homicide would await any physician who gave a patient poison or otherwise tried to end his life, even though the physician wanted to be merciful and relieve the patient's suffering. And legal developments -- such as the recent Baby Doe legislation -- have restricted the circumstances in which treatment may be withdrawn and death allowed to occur without any human assistance.

Yet, at the same time that physicians' choices about dying patients are being circumscribed, 11 states have adopted statutes commanding that medical means be used to execute prisoners under capital sentences. Such executions are being challenged in a case argued before the Supreme Court Monday.

At its core, the case asks whether physicians -- or anyone using their techniques -- should kill people by lethal injections, although the justices need only rule on a narrow question of administrative law: Was the appellate court correct in ordering the Food and Drug Administration to investigate the use for capital punishment of drugs that the FDA has only approved for recognized medical purposes?

It would be a mistake, however, to treat this case as involving merely arcane questions about the scope of judicial review of federal agencies' discretionary decisions. At issue is a fundamental ethical standard that reassures us all about the commitment of health care personnel to our welfare -- and continued life.

The FDA finds itself confronted with this issue because state legislators decided that one way to blunt opposition to capital punishment was to prescribe a method of execution that would seem less grisly than hanging or electrocution. Unfortunately, the hope that lethal injection offers a swift and humane form of killing may be illusory because the drugs used to sedate, anesthetize and then paralyze prisoners have never been tested for this purpose.

Anesthesiologists who have looked at the subject can find no scientific support for believing that the methods being used are effective for a quick and painless execution. Rather than going gently to sleep (never to awake), prisoners may die in pain, aware of suffocating and of other side effects of the drugs. (Ironically, in a previous case the FDA itself had insisted on proof of the safety and effectiveness of the drugs used by veterinarians to kill domestic animals, to ensure that they would consistently provide painless death.)

The lack of scientific tests for the techniques used in capital punishment is exacerbated because it is unlikely that the people administering the lethal injections will be properly prepared. The sorry lessons of recent history teach medical personnel to steer clear of involvement.

The Nazi campaign of "euthanasia" grew out of the writings of distinguished German professionals in the 1920s. Worse, physicians played leading roles in the design and operation of Auschwitz and other death camps. In more recent years, the world's conscience has been shocked by medical complicity in the torture carried out in Chile, Iran and Argentina.

As the American Medical Association recently concluded, "A physician . . . should not be a participant in a legally authorized execution." Since most health professionals disapprove of the perversion of medical knowledge, not merely doctors' physical presence, it seems unlikely that executors employing lethal injections will be trained in all the skills necessary for painless killing.

Do we really want to encourage physicians and nurses to abandon their opposition? I think not. As the eminent psychiatrist and cultural historian, Robert Jay Lifton, concludes after a searching examination of medical involvement in Nazi executions, the professions' ethical standards are needed if we are to avoid the "breakdown, or threatened breakdown, of distinctions between healing and killing."

Legislation mandating lethal injection for capital punishment can thus be faulted on two grounds. First, it rests on false premises. There is good reason to fear that the deaths will not be swift and painless, as expected by the public, including jurors and judges -- especially when the executions are performed by ill- trained amateurs.

Yet perhaps of even greater significance for society at large is the potential harm that lethal injection legislation can do to medical professionals' dedication to using the increasing powers of biomedical science for human welfare. By using medical knowledge and personnel to kill people, we do more than undermine the emerging standards and procedures for good, ethical decision-making about the sick and dying. We also set off toward a terrifying land where the white gowns of physicians are covered by the black hoods of executioners.