Criminal law is often seen as in instrument of social justice by persons who are not really aware of its limits or of the philosophical disputes concerning its proper purpose.

The criminal law is only a part of a broader system of legal justice. When a worker is injured on the job, the civil lay may require that the employer compensate the worker. But when individuals commit "crimes" - assault, arson, or murder - they are liable also to the penalty of imprisonment.

Imprisonment of the convicted lawbreaker symbolizes moral condemnation by society of the crime. Such punitive treatment is intented not merely to confine, but also to cast the criminal so confined into disgrace. Criminal law, say some philosophers, contributes to the moral conscience of humanity. The moral denunciation expressed by imprisonment presumably deepens our awareness that acts such as murder, arson, or kidnapings are morally reprehensible.

But, critics claim, criminal law induces an opposite effect. It encourages feelings of vengeance and in places of imprisonment - outside of society - brutality is at home. Moreover, our law is not even-handed. An innocent defendant falsey accused is, if unable to pay for skilled counsel, more likely to be convicted.

Should all acts belived immoral by the community be prohibited, as crimes, by law? Remember that in the past, witchcraft was believed immoral by some communities, and punished - dreadfully - by law, as a crime.

Today, criminal law lags behind changing moral attitudes, especially in such matters as sex and drug-taking. In many states, most forms of gambling are still a criminal offense.

Should the law - like a parent - coerce an individual, for his or her own good? Some state laws, for example, require a motorcyclist to wear a helmet. But the attorney general of New Mexico dissented from such "legal paternalism" by stating that a bareheaded cyclist may injure himself but not "his fellow man."

Or, as the 19th-Century philosopher John Stuart Mill declared, law may coerce a person "to prevent harm to others." But, "over himself, the individual is sovereign." Mill would insist that "victimless crimes" - for example, gambling, homosexual acts, the drug-taking - are private matters, that is, "not the law's business."

But is it true that cylists who refuse helmets can only hurt themselves? If injured, they - like the motorists who disdain seat belts - may cause suffering to their families, or need hospital care at public expense.

Similarly, one's use of hair sprays may hurt others if such sprays contaminate the atmosphere. Should their use, therefore, be made a criminal act? There may be far fewer private matters in our society than are dreamt of in Mill's philosophy.

According to the utilitarian philosopher Jeremy Bentham, the criminal law, like all human institutions, should be fashioned to yield "the greatest happiness" - or the least unhappiness - for the community. The threat of punishment, utilitarians hope, would deter a rational person tempted to break the law. Hence that threat reduces the misery and insecurity wrought by crime.

A utilitarian, appraising the value of legal punishment, is like an individual contemplating a painful dental procedure. By submitting to pain now, the dental patient avoids greater pain in the future. The utilitarian views punishment in a similar fashion. By inflicting misery on criminals now, society prevents greater future misery to potential victims of crime.

Many persons measure the criminals now, society prevents greater future misery to potential victims of crime.

Many persons measure the success - or failure - of legal punishment by its effectiveness in reducing crime. But it is hard to tell whether legal punishment is effective as a deterrent. How often does the threat of imprisonment stop the criminal (once punished), or the ordinary citizen (never punished), from breaking the law? Do you know how many crimes you would commit in a society without legal punishment?

Even if punishment accomplished the deterrent task assigned by utilitarians, critics claim that penalties devised by utilitarians might still not achieve justice.

Imagine, for example, that six months of preventive detention effectively deterred many 18-year-old high-school dropouts from future crime. Indeed, by comparison with other crime control methods, such preventive punishment minimized social costs most effectively. On a cost-benefit basis, the utilitarian would opt for preventive detention.

But most of these 18-year-olds never committed a crime. They do not deserve to be punished.

Thus the utilitarian philosopher is committed to undeserved punishment - surely an injustice. There is a considerable moral difference between an individual voluntarily deciding to endure pain at the dentist, and society - through coercion - deciding to punish innocent persons for future benefits.

Perhaps this preventive detention example seems far-fetched. But it should be remembered that our society has engaged in massive preventive detention, for example, the internment during World War II of innocent Americans whose only "crime" was their Japanese ancestry. Surely they did not deserve to be punished, either.

Retributivist philosophers, such as Immanuel Kant, George Hegel and Francis Bradley, find the utilitarian perspective on punishment morally unacceptable. According to Kant's principle of humanity, a person should never be used merely as a means to an end.

Punishment, declares the retributivist, should therefore never be inflicted for the welfare of the community.

Criminals should be punished because they deserve it, and for no other reason.

Some critics see retributive punishment as vengeance - an uncivilized response. But for a retributivist philosopher, punishment is administered not to take vengeance but to balance the scales of justice. Even the punished criminal, claims Kant, knows in his heart that justice has been done.

On some occasions, most of us think like retributivists. Recall the Nazi war criminals convicted at Nuremberg. Suppose that punishing them did not prevent similar crimes, or indeed, do any future good for society. Should they have been excused from punishment? Many would, in this case, join with the retributivist: Punish them because they deserve it.

But should ordinary offenders be punished, just because they deserve it? Suppose, just for the sake of argument, it were proven that punishment did not really reduce the extent of crime. (Any temporary crime reduction accomplished by isolating offenders in prison was canceled by the tendency of former criminals - unemployable because of their records - to commit more crimes.) In that case, I suggest that society has no moral obligation to pay for penal institutions.

Why support a prison instead of a hospital, unless prisons, like hospitals, are necessary to prevent human misery?

Or suppose an alternative to punishment, for example, vocational therapy, were proven less costly and more effective in preventing crime. Surely, opting for that alternative makes good moral sense.

Let us grant that retributivists were right when they faulted utilitarians for flouting Kant's principle of humanity. Criminal punishment, if morally acceptable, should surely be deserved.

But the utilitarians were not altogether wrong. Criminal punishment, if morally acceptable, should also show itself capable in the enterprise of minimizing human pain.