Sen. Richard Durbin, D-Ill., started something when he asked Attorney General nominee Michael Mukasey whether he considers waterboarding to be torture. When the nominee declined to give a definitive answer, the matter cascaded into a confirmation-threatening imbroglio.

Within a day, all of the Judiciary Committee Democrats as well as Republican Sen. Arlen Specter, R-Pa., had signed a letter demanding clarification. Sens. Lindsay Graham, R-S.C., and John McCain, R-Ariz., then further complicated Mukasey's position by denouncing waterboarding and calling upon the would-be attorney general to do the same.

The question of just what does and does not qualify as torture is a vexed one in American law. The U.S. is a signatory to the Geneva Convention, the International Covenant on Civil and Political Rights and the U.N. Convention Against Torture and Cruel, Inhuman and Degrading Treatment -- all of which forbid torture.

Under the U.S. Constitution, treaties are the supreme law of the land. But that hardly settles the matter. Defining torture requires teasing it out of court decisions and legal memoranda (like the so-called "torture memo" issued by the Justice Department in 2002 and later withdrawn), as well as statutory language. As Andrew McCarthy explained in National Review, torture has been variously described as "specifically intended to inflict severe physical or mental pain or suffering" or "intense, lasting and heinous agony."

Waterboarding apparently involves placing a person on his back on a seesaw board, tilting him backward, covering his face with a cloth, and then pouring water into his mouth and nose so that he feels as if he is going to drown. It sounds pretty bad -- but is it torture? The military has required our pilots to undergo it to prepare them for interrogation upon capture. That says something. On the other hand, a pilot knows what an enemy combatant presumably does not: that he will live to tell the tale.

What does the law say about waterboarding? As McCarthy points out, Congress had the opportunity in the Detainee Treatment Act of 2005 and again in the Military Commissions Act of 2006 to specifically forbid the practice but chose not to do so. McCarthy writes: "It is ironic . . . that the same elected officials now demanding a definitive answer from Judge Mukasey have failed to give us one themselves . . . "

By showboating their opposition to this technique, the senators are placing Mukasey in an impossible position. If he declares that the practice is torture then he may be putting the interrogators who used it (on advice from the Justice Department) in legal jeopardy. And in light of the confused and vague nature of the law, Mukasey would need access to classified information about exactly what was done in order to reach a judgment on its legality. It would be irresponsible of him to opine on the matter based only on rumors in the newspapers of what may have been done to specific detainees.

This is a deadly serious issue that demands thoughtful consideration from every American and particularly from elected officials. In a war not against massed armies or nations but against small cells of terrorists, interrogation is a key weapon. It's so easy to, in John McCain's words, "take the moral high ground" and denounce any sort of torture under all circumstances. But is it really the moral high ground?

We can all agree that under normal circumstances, harsh techniques are neither desirable nor necessary. But what about the ticking time bomb scenario? If we were to capture a key al Qaeda operative who we had strong reason to believe had knowledge of a dirty bomb buried under an American city, and we had only hours to get information out of him, would it be morally correct to waterboard and possibly save hundreds or thousands of lives, or to refrain? Anyone who claims that the answer is obvious hasn't really thought it through. And for those who object that a person under duress will say anything, the question is, won't that "anything" include the truth?

Nor is the argument that permitting waterboarding will "free up" our enemies to do the same to our people convincing. They tend to string up or behead the Americans they capture. Waterboarding would be an unqualified improvement.

Congress could have debated these matters but declined. Now senatorial moral preening may derail an excellent nominee. The country will be ill served if that happens.