Two years ago, while government interrogators were attempting to wring information from alleged al Qaeda members imprisoned at Guantanamo Bay, Cuba, and elsewhere, the Justice Department prepared a legal memorandum on the use of torture during interrogation. The CIA had sought guidance from the White House because it wanted to conduct more aggressive interrogations than those allowed before Sept. 11, 2001. As we now know, the White House in turn requested the legal opinion from the Justice Department. In August 2002, Justice's Office Of Legal Counsel, led by Jay S. Bybee, produced a 50-page memo that essentially said the president could authorize torture even though our laws and treaties prohibit it. Bybee reached this conclusion, quite simply, by distorting the law.

We often think of lawyers as advocates, such as courtroom lawyers who make zealous arguments that may or may not convince a judge. But the Department of Justice lawyers who wrote the memo on interrogation and torture were acting as advisers. As such, their responsibility was to advise their "client," the executive branch, as to what the law requires. Lawyers routinely provide clients with such "opinion letters" to help sort out whether proposed conduct is legal, illegal or somewhere in between.

The Justice Department memo assured the Bush administration of three things: First, that interrogators could cause a lot of pain without crossing the line to torture. Second, that even though the United States criminalizes torture and has signed a treaty outlawing it, interrogators could torture prisoners as long as the president authorized it. Third, that even if those interrogators were later prosecuted for engaging in torture, there were legal defenses they could use to avoid accountability.

Bybee's conclusions rest upon three stunning legal contortions, requiring no less than an entirely new definition of torture, a distortion of fundamental constitutional law and a new approach to the application of international law.

The first contortion redefines torture in a manner wholly divorced from U.S. and international practice. Bybee came up with what he called an "aggressive interpretation as to what amounts to torture," asserting that for an act to constitute torture, it must be of an "extreme nature" in that it "must inflict pain that is difficult to endure." His memo explains that "physical pain amounting to torture must be equivalent in intensity to the pain accompanying serious physical injury, such as organ failure, impairment of bodily function, or even death." The memo would, if applied, severely limit the possibility that mental pain or suffering can amount to torture, stating that "it must result in significant psychological harm of significant duration, e.g., lasting for months or even years." This extreme definition departs radically from both U.S. and international understandings of the prohibition against torture.

The Justice Department construction of torture also creates a truly remarkable "self-defense" exception for torture. It reasons that if a U.S. interrogator "were to harm an enemy combatant during an interrogation . . . he would be doing so in order to prevent further attacks on the United States by the al Qaeda terrorist network." An interrogator's actions, it says, would be "justified by the executive branch's constitutional authority to protect the nation from attack." This is utter nonsense. An individual cannot invoke the executive branch's authority to torture because the executive itself lacks that authority. There is no self-defense exception to torture, either by an individual or by the state. While there may be some debate around the edges concerning what constitutes torture, there is consensus on its basic elements, which distinguish torture from other forms of abuse. These elements are defined by the international Convention Against Torture, to which the United States is a party. They include: the infliction of "severe" pain and suffering with the intention of doing harm for a specific purpose (such as obtaining information during interrogations), carried out by "a public official or other person acting in an official capacity," such as in a prison.

By ratifying the Convention Against Torture in 1994, the United States committed itself to criminalizing torture, in addition to providing civil remedies for torture victims. The Bybee memo subverts that commitment by adopting an unsupported, narrow definition of torture. Under the convention, this country also undertook to prevent "cruel, inhuman or degrading treatment" that falls short of torture. There are no exceptions. And yet the Justice Department memo reads like an invitation to engage in exactly that kind of conduct.

The second contortion would take U.S. constitutional law back 800 years, to a time before the Magna Carta, and create an executive office that can act arbitrarily, beyond the control of Congress. The memo asserts that the president can act however he sees fit during war, even if U.S. law and international treaties prohibit such conduct. It zeroes in on a single constitutional phrase -- "The President shall be Commander in Chief of the Army and Navy" -- and boldly asserts that the president is all-powerful in things military. "The president enjoys complete discretion in the exercise of his commander in chief authority," it says, and "Congress may no more regulate the president's ability to detain and interrogate enemy combatants than it may regulate his ability to direct troop movements on the battlefield."

But Bybee could have reached these conclusions only by ignoring the rest of the Constitution, including the numerous military-related roles that it assigns to Congress, such as making rules "concerning captures on land and water" and "for the government and regulation of the land and naval forces."

This way of thinking, which we have come to think of as the "absolute commander-in-chief argument" also flies in the face of years of Supreme Court precedent in which the court has repeatedly rejected expansive claims of unilateral control by the executive branch. In Youngstown Sheet and Tube Co. v. Sawyer, for example, the Supreme Court rejected President Harry S. Truman's unilateral attempt to take over steel mills during the Korean War. While the president has significant latitude in the conduct of foreign affairs, such latitude has been constrained by congressional legislation and judicial decisions. The Justice Department memo ignores this history.

The final contortion concerns the memo's overall assertion that the president is above international law. Nothing could be further from the truth. Under the Constitution, the president and members of the executive branch are bound to faithfully execute the law, including international law to which it has agreed. This is not optional.

The Convention Against Torture provides that "no exceptional circumstances whatsoever, whether a state of war or a threat of war, internal political instability or any other public emergency, may be invoked as a justification for torture." And Common Article 3 of the Geneva Conventions provides that the rights and duties concerning fundamental humane treatment apply whether a person detained is a prisoner of war, unprivileged belligerent, terrorist or ordinary civilian.

It's hard to believe that the memo was poorly researched, so it makes one wonder whether the Justice Department was being disingenuous. A lawyer who is arguing to a court is allowed to be disingenuous because it is up to the judge to evaluate that argument against the adversary's and decide what the law is. But a lawyer who is writing an opinion letter is ethically bound to be frank.

How could Bybee have written such a scandalous opinion? Lawyers who tell their clients what they want to hear -- rather than the advice they need -- are sometimes rewarded with career advancement. Last year, Jay Bybee was appointed to the U.S. Court of Appeals for the 9th Circuit.

There is a proud tradition of lawyers bravely telling clients not what they want to hear, but what the law requires. Judge Bybee's actions stand in stark contrast to the best traditions of the bar.

Authors' e-mails:

Kathleen Clark is a professor of legal ethics at Washington University in St. Louis. Julie Mertus is an associate professor and co-director of the ethics, peace and global affairs program at American University and the author of "Bait and Switch: Human Rights and U.S. Foreign Policy" (Routledge).