Physicians who promote the extension of sexual predator statutes, or even endorse them, must have lost their moral compass. It is not hard to understand the public's wish to see repeat offenders locked up and prevented from inflicting further harm upon society. The public probably couldn't care less whether the confinement is in a prison or a mental hospital, though people might have a few qualms if they understood that the hospital costs are two to five times higher.

It is harder to understand, however, why physicians would be willing to use their medical authority for preventive detention and punishment. Involuntary hospitalization was designed to ensure that those who are seriously mentally ill receive humane care and treatment when they are unable to care for themselves. It was not designed to be an arm of the criminal justice system.

Recently, some states have created a new kind of civil commitment that permits a class of criminals--repeat sexual offenders--to be transferred at the end of their sentences from prisons to hospitals and detained there until they can prove they are no longer dangerous. The decision to commit can be made on the basis of the behavior that resulted in their original arrest. No evidence of recent dangerous behavior is required. The laws are so broad as to include exhibitionists as well as sexual sadists and other criminals, as long as there was a sexual component to the crime. Now, some justice and mental health officials want to extend this to certain murderers so that they, too, would be indefinitely confined under the label of "mentally abnormal."

Because the element of mental abnormality is so vague, it allows the state to select the criminal behavior it would like to target and then find some disorder that will be present in certain felons. It is not that it is impossible to diagnose potentially dangerous mental abnormalities; it is that the process is an abuse of psychiatry.

About 15 states have adopted these "sexually violent predator" commitment statutes, upheld in 1997 as constitutional by a 5-to-4 U.S. Supreme Court decision in Kansas v. Hendricks. Leroy Hendricks is a pedophile who was arrested and imprisoned several times for molesting children. After he had finished serving his time--and although he had consistently been found legally sane and competent--he was sent to a state hospital for the criminally mentally ill based on his mental disorder of pedophilia and presumed continuing inability to control his behavior. This amounts to using physicians and the mental health system to extend a criminal's prison sentence indefinitely.

Repeat sex offenders have always outraged the public. In an earlier era of therapeutic optimism--roughly the 1940s and '50s--more than half the states had laws confining such criminals to hospitals instead of prisons so that they could obtain treatment. When treatment did not work well enough, most states repealed or suspended these statutes and used "indeterminate" sentences such as "one day to life" to keep such offenders in prison.

But in the '70s, sentencing reforms repudiated a system that could be so prone to abuse. It was replaced with "determinate sentencing," wherein convicted felons receive fixed sentences and are required to serve the entire time in prison.

But the inflexibility of determinate sentencing, in turn, set the stage for the release of offenders who may repeat patterns of antisocial behavior. Following a particularly vicious crime by a sadistic pedophile who had already served his full "determinate sentence" in Washington, that state and others began to pass sexual predator laws.

What is problematic about these statutes is that the confinement in a mental hospital would begin only after the offender's entire prison sentence was served.

An additional problem, from a medical viewpoint, is the statutes' broad definition of mental disorder. It could be met by a diagnosis, such as antisocial personality disorder (APD), that generally has not been used as a basis for civil commitment. APD can be diagnosed when there is a history of childhood behavioral problems coupled with later adult criminal activity. It is not very precise or reliable; in fact, most criminals could be given this diagnosis. Since many are also recidivists, it could be argued that they are candidates for commitment at the end of their sentences.

In its Task Force Report on Sexually Dangerous Offenders this year, the American Psychiatric Association said that the new statutes are a misuse of psychiatry because they have the effect of defining criminal behavior as a mental illness. Moreover, they do not base criteria for hospitalization on psychiatric research or therapeutic findings.

While the Kansas case specifically involved a pedophile, statutes in other states, such as Wisconsin, have included rapists with antisocial personality disorder. Now we are seeing proposed extensions to other criminal behavior, such as murder. Why stop there? In some countries, political dissidents have been labeled as mentally ill.

There are a host of problems surrounding the implementation of these civil commitment programs. Aside from the additional expenses of screening, legally adjudicating and civilly committing these inmates, there are enormous logistical problems. These "patients" require maximum-security settings. They cannot be mixed with actual mentally ill patients, since they often abuse them.

There are many unmet health needs in our prisons as it is. We need to identify serious psychiatric disorders that warrant treatment regardless of the crime committed. The proposed programs for murderers, however, are not seen as a mechanism to provide necessary treatment but rather to extend punishment and protect society. These statutes cloak their quasi-punitive intent in the language of medical treatment. These are appropriate societal goals but not at the expense of undermining the legitimacy of the medical model of commitment.

Criminal recidivists pose an enormous social problem to society. But it is a problem that needs to be addressed by the criminal justice system--not the medical profession. The system needs to be given resources to craft broader criminal penalty statutes, enabling longer sentences, as well as to provide better probation and parole monitoring of such individuals.

Mental health treatment may be a helpful adjunct in some cases where the individual is interested or the diagnosis warrants it, but it should not be distorted into being used as a tool of the state. Just as physicians should not participate in legally authorized executions, we should not condone the misuse of our professional values and erode patient trust by transforming our roles from healers to jailers.

Howard Zonana, a professor of psychiatry and of law at Yale University, is the medical director of the American Academy of Psychiatry and the Law.