The death penalty is not intrinsically immoral. Public authorities have the right to execute murderers, and may exercise that right, if the correct conditions are met. This is the common and historic view of humanity, as well as the teaching of the Catholic Church.

Were those conditions met in the case of Saddam Hussein, a brutal dictator convicted of murder, torture, and crimes against humanity? One might think that, if the death penalty is ever justified, then it was justified in his case. Yet many people were puzzled when a Vatican spokesman referred to his execution as “tragic.”

Let’s review the teaching of the Church, which views capital punishment as an instance of punishment generally. This teaching may be broken down into four parts: just desserts; substitutability; common good; and commensurability.

Just desserts. People deserve to have done to them what they do to others. If they help others, then they deserve praise and a reward; if they harm others, then they deserve blame and punishment, in retribution.

By the same token, if someone kills another, then, in the nature of things, he deserves to be put to death. “If anyone sheds the blood of man, by man shall his blood be shed; for in the image of God has man been made,” (Gen 9:6.) That is why capital punishment can never be a “crime,” and the death penalty is never murder--because there is a distinction in kind between innocence and guilt.

As the Roman Catechism states: “Another kind of lawful slaying belongs to the civil authorities, to whom is entrusted power of life and death, by the legal and judicious exercise of which they punish the guilty and protect the innocent. The just use of this power, far from involving the crime of murder, is an act of paramount obedience to this Commandment which prohibits murder.”

Note that the distinction between innocence and guilt is a safeguard of freedom, as it implies a limit on governmental authority: the state may never licitly take the life of an innocent human being, or --as in legal abortion--stand idly by while one person takes the life of another.

Substitutability. The simplest way of giving someone his just desserts is through the “lex talionis,” or “an eye for an eye”: if you pluck out someone’s eye, then your eye is to be plucked out in retribution. However, we recognize that, it is most humane to substitute whenever possible an equivalent bloodless punishment. We do not pluck out a criminal’s eye, but we put him in prison for 10 or 20 years.

Similarly, the simplest way to punish a murderer is to put him to death, but we recognize that, in most cases if not in all, as regards retribution, life imprisonment fully substitutes for the death penalty. (If it did not, then we would have to take the insane view that we would be unjust unless we executed each and every murderer.) Thus, whenever it is possible to put a murderer in prison for life instead of executing him, while satisfying the requirements of the common good, then we should do that.

The common good. Public authorities have the right to punish anyone who has committed a crime with as much severity as the crime deserves. But they should exercise that right, only insofar as doing so protects the common good and advances the purposes of punishment. The purposes of punishment include such commonly recognized things as deterrence, upholding the rule of law, providing an example for the purpose of educating citizens, and protecting society from aggressors. For example, in Germany during World War II, hundreds of thousands of citizens were implicated in murder. But it would have harmed the common good to punish all of these, even though they deserved it. Thus the Allies punished only the leaders.

Commensurability. In promoting the common good, public authorities may only apply punishments that are commensurate to the end they wish to achieve. Thus, in particular, the penalty of death can be applied for no other purpose than to save others from death. The death penalty may not be used to protect property, or even to inspire a just fear or to instruct. It may be used only to protect life. This is analogous to the principle that police officers may use lethal force only when that is necessary to protect someone’s life.

So then, taking all of this into account, what should we say about Saddam Hussein’s execution?

There seems to be a strong argument, on Catholic principles, that his execution was justified. It is not clear that life imprisonment for Hussein was an available alternative, because Iraqi society is so unstable. Was it really a sure thing that he would spend the rest of his years in prison?

Furthermore, even if life imprisonment was a genuine possibility, someone might argue that Hussein’s continued life in prison would serve as a threat to the lives of others, because he would continue to incite others to insurrection and murder. At his trial, Hussein solemnly pronounced that he would one day get free from prison, to take vengeance on those who arrested him and supported the Iraqi government. His supporters would arguably continue to act on that threat, so long as he remained alive.

But ultimately even a justifiable execution is tragic, in the way that all human evil is tragic.

Michael Pakaluk is a professor of philosophy at Clark University.