If you've noticed that the craziest killers in our society are usually convicted and rarely found not guilty by reason of insanity, then you are probably an astute observer of American criminal trials.

Juries rejected insanity pleas from mass killers Richard Speck, Charles Manson and John Wayne Gacy. Those verdicts are testaments to the distrust and hostility that jurors have for the medical and legal professions. The verdicts are also evidence of those jurors' good sense.

Mass murderers would seem to present classic cases for an insanity defense, yet time after time these pleas are rejected by juries. Although the legal definition varies from state to state, it is fair to generalize that the insanity defense is one which questions whether the defendant was capable of exercising reason at the time he committed the crime or whether mental disease robbed him of free will and the ability to choose not to commit the crime.

Expert medical testimony was offered on behalf of Speck, Manson and Gacy, but the state also was able to offer its own experts who claimed that the defendants were sane. In each case, the juries found the mass murderers sane and responsible for their criminal acts.

No one would suggest that these three presented pictures of perfect mental health. Each in his own way could have been the American mass murderer of the century were it not our misfortune that they iall lived and committed their crimes in our time.

Speck's mad rampage one July night in 1966 left a southeast Chicago apartment riddled with the blood of eight brutally murdered young nurses. Manson cast his spell of sex and evil across his cult of misfits best remembered today for the savage slayings of Sharon Tate and her companions.

John Gacy's crimes, which were just discovered last year, involved the bizarre massacre of yet untotaled young men with whom he had sexual relations. He then buried many of their bodies in the basement and around the foundation of his suburban home. Gacy was charged with murdering more people than anyone else in American history.

We can be assured that the jurors realized, just as we do, that persons such as Speck, Manson and Gacy were mentally ill. In fact, they may have been psychotic. What those jurors acknowledged, however, unlike many doctors and lawyers, was that just because those men were mentally ill or psychotic did not mean that they were legally insane.

Insanity is not a medical term. It is a legal term. A person who is mentally ill or even psychotic may still be legally sane and consequently responsible for his criminal acts. Unlike psychiatry, the law is premised upon a human's essential rationality and ability to exercise choice.

The legal definitions of insanity are properly rigid, intending to weed out all those criminals who, though mentally ill, are able to refrain from committing crimes. Only those very few who cannot distinguish between right and wrong or who are unable to conform to society's laws are not responsible for their behavior and are not guilty by reason of insanity.

All too often judges wrongfully conclude, or are wrongfully pursuaded by psychiatric jargon, that one who is mentally ill is automatically insane and should not be held responsible. The much maligned American jury appears capable of cutting through the jargon and making the hard decison that the law demands. Jurors made those decisions and found Speck, Manson and Gacy responsible for their crimes and guilty of murder.

When those juries deliberated the fates of the three mass murderers, they represented all of us. We can make two legitimate demands on the criminal justice system: that the courts and the police will combine to provide us with the maximum possible safety in our homes and on the streets, and that the system will treat us fairly if we ever become embroiled in it as defendants.

Although instructed by the judge not to do so, during their deliberations these juries probably questioned whether their safety and their families' safety would be protected adequately if the defendants were found not guilty by reason of insanity. The answer to that question had to be a resounding "No!" r

The fate of criminally insane defendents endangers the safety of our communities and assures that some criminally insane persons will be back on the streets in a relatively short period of time with the opportunity to bring more tragedy into the lives of innocent persons.

Recently, it was underscored by the news media that persons adjudged criminally insane in Ohio are back on the street on an average of less than two years after their trials. Nor is it any better in the rest of the country.

It should be inconceivable that one who was found criminally insane using the strict criminal standard would not be mentally ill and dangerous. It is further unlikely that such a person would show a marked and rapid improvement. But it is only inconceivable and unlikely if the initial determination that the defendant was criminally insane was a correct decision.

This country has a great tradition of independent juries charged with a heavy responsibility of reaching their own conclusions. Jurors are free to accept or reject the testimony of expert witnesses such as psychiatrists and psychologists, just as they are free to accept or reject the testimony of any other witness.

Jurors who tried Speck, Manson and Gacy understood what I like to call the great American legal maxim: All people who commit crimes like that are crazy, but not all crazy people are insane.