In recent weeks, the news media have reported a number of stories about the kidnapping and slaying of children, including Samantha Runnion, a 5-year-old California girl. I cannot personally imagine the pain her parents and neighbors and friends must feel at such a heinous crime. What has been unusual in the Runnion case, however, is the reaction of a lawyer, John Pozza, who practices in Temecula.

In 2001, Pozza represented the man accused of killing Samantha, a man named Alejandro Avila, in a sexual molestation charge involving two small girls. In that case, the jury found Avila not guilty. Avila, of course, was then released and went on, allegedly to kill Samantha. According to a report by CNN, Pozza said, upon learning of Avila’s alleged new crimes: “It has thrown my entire world off course. It has stopped me on a personal level to contemplate whether I did anything wrong.”

Did he? One of the most basic questions every criminal lawyer faces is whether he ought to represent defendants in criminal trials whom he believes to be guilty. The answer our system gives is that he may do so, if he wants to, and that someone must do so, in order to guarantee that the defendant’s legal rights are preserved. Of course, a lawyer may not lie for a client; nor may he assist a client in lying, but a lawyer may properly represent a client charged with even such heinous crimes those with which Mr. Avila is charged and may do so even if he believes that the client is, in fact, guilty.

Indeed, it is important to remember that in our system of justice, a person is innocent until proven guilty, and that only occurs when a court has determined such guilt. Of course, a lawyer is not required to defend someone he believes to be guilty (unless he is required to do so by a court) and always has the right to decline representation or even to withdraw from representation if this would be repugnant to him. But those lawyers who are willing to take on the defense of unpopular clients charged with terrible crimes are considered to have behaved in an ethical manner.

Why would any decent human being want to represent someone accused of child molestation? The answer, I think, is that lawyers understand that our system of justice is an adversarial system that looks to each side to present its best case within the limits of the rules of procedure and to a judge and/or jury to listen to each side and to make a determination of guilt or innocence. An absolutely necessary prerequisite to making such a system work fairly and expeditiously is that each side have adequate legal representation.

If no lawyer was willing to defend people charged with horrible crimes, then our justice system simply wouldn’t work and would more closely resemble the Spanish Inquisition or the Stalinist show trials than traditional Anglo-American ideas about justice under the law. In fact, one can argue that those lawyers who do represent defendants charged with terrible crimes, even those so repugnant that the general public calls out for their blood, are precisely those lawyers who are making the greatest personal sacrifice to ensure that the legal system is working.

Certainly, this would seem to be the case with Mr. Pozza. It is obvious he is going through terrible personal agonies because he feels guilty that he helped Avila stay out of prison. In addition, according to news reports, Pozza has received a number of threats simply because he defended Avila last year. Pozza may well be forced to leave his home and his career in Temecula and start again elsewhere, all because he did his job in representing Avila.

Any lawyer or judge will tell you that the American justice system is far from perfect. Innocent men and women are found guilty, and guilty men and women are found innocent. But our justice system is a product of our own human frailty. Nothing we do is perfect and it is foolish to think that we can achieve perfection in human endeavors. Certainly, we could devise a justice system which tended to err more on the side of conviction than at present, but most Americans would not accept such a system. It would, in effect, be tyrannous.

It is just terribly tragic, however, that the system’s imperfections do, on occasion, permit dangerous men and women to go free and ultimately, perhaps, lead to the death of innocents. Whether this will be the case as to Avila will be decided by a jury in the new case against him. But the lawyers, both for the defense and the prosecution, are not to blame, no more so that the judge or the jury. All of these participants in the justice system, on the contrary, have done what we, as a society, require of them. And for that, we should be grateful.

Mike Hoeflich is a professor in the Kansas University School of Law.