When the Nazis came to power in Germany in 1933 and proceeded to carry out their savagery, many in the outside world asked how this could have happened in the land of Goethe and Beethoven. Would the people of other societies as readily accept tyranny? Sinclair Lewis, in 1935, imagined Americans turning to dictatorship under the pressures of economic distress in the Depression. He called his novel, ironically, It Can't Happen Here.

Hannah Arendt and many others have stripped us, since then, of confidence that people will resist evil in times of fear. When Serbs and Rwandan Hutus were told that they were threatened, they slaughtered their neighbors. Lately Philip Roth was plausible enough when he imagined anti-Semitism surging after an isolationist America elected Charles Lindbergh as President in 1940.

But it still comes as a shock to discover that American leaders will open the way for the torture of prisoners, that lawyers will invent justifications for it, that the President of the United States will strenuously resist legislation prohibiting cruel, inhuman or degrading treatment of prisoners–and that much of the American public will be indifferent to what is being done in its name.

The pictures from Abu Ghraib, first shown to the public on April 28, 2004, evoked a powerful reaction. Americans were outraged when they saw grinning US soldiers tormenting Iraqi prisoners. But it was seeing the mistreatment that produced the outrage, or so we must now conclude. Since then the Bush Administration and its lawyers have prevented the release of any more photographs or videotapes. And the public has not reacted similarly to the disclosure, without pictures, of worse actions, including murder.

The American Civil Liberties Union released documents on forty-four deaths of prisoners in US custody, twenty-one of them officially classified as homicides. For example, an Iraqi prisoner died while being interrogated in 2004. He had been deprived of sleep, exposed to extreme temperatures, doused with cold water and kept hooded. The official report said hypothermia may have contributed to his death.

Writing recently in The New Yorker, Jane Mayer described the killing of an Iraqi prisoner, Manadel al-Jamadi, in Abu Ghraib in 2003. His head was covered with a plastic bag, and he was shackled in a position that led to his asphyxiation. The death was classified as a homicide. But so far no charges have been brought by the Justice Department against the man who had custody of the prisoner, a CIA officer named Mark Swanner.

In addition to murder and torture, humiliation and indignity have been widely used as aids to interrogation. Time quoted at length earlier this year from the official log of how one prisoner in Guantánamo Bay, Cuba, was interrogated. Over a period of weeks he was questioned for as long as twenty hours at a stretch, forbidden to urinate until finally he "went" on himself, made to bark like a dog. His treatment was an exercise in humiliation. Other reports have described prisoners chained hand and foot to the floor for twenty-four hours, until they urinated and defecated on themselves.

Several provisions of law forbid not only torture but humiliation of prisoners. The Geneva Conventions prohibit "outrages upon personal dignity, in particular humiliating or degrading treatment" of war captives. The UN Convention Against Torture condemns "cruel, inhuman or degrading treatment"–and Congress enforced the provisions of the convention in a criminal statute. The Uniform Code of Military Justice makes cruelty, oppression or "maltreatment" of prisoners by US forces a crime.

Then how can it be that hundreds of Americans, at a modest estimate, have been involved in the tormenting of prisoners, using the "waterboard" technique to bring them to the brink of drowning, beating them or worse? The answer is that the cue for these outrages came from the top of the American government.

Soon after the terrorist attacks of September 11, 2001, the Justice Department–then under Attorney General John Ashcroft–began producing memorandums that opened the way to torture and mistreatment of prisoners. The memos gave an extremely narrow definition of torture: producing pain equivalent to that from "serious physical injury, such as organ failure, impairment of bodily function, or even death." They argued that the President, in his constitutional role as Commander in Chief, had the power to order the use of torture no matter what treaties or US statutes said. And they said the Geneva Conventions did not apply to the prisoners at Guantánamo.

It is important to note that these legal opinions came almost entirely from political appointees, not longtime Justice Department lawyers. Similarly, Defense Secretary Rumsfeld and his aides overrode objections from most military lawyers and other officers. Secretary of State Colin Powell, former chair of the Joint Chiefs of Staff, was a notable opponent of the memos.

The very purpose of these radical legal opinions was to override objections to torture from those in the services and the law who wanted to carry on the American tradition of humane treatment of prisoners. And there was a further, crucial purpose: to immunize those who actually carried out torture or inhumane treatment from criminal prosecution. If charged, they could maintain that their actions were authorized from above.

One more legal interpretation by the Bush lawyers, especially clever, should be mentioned: It concluded that the Convention Against Torture (and its enforcement by criminal statute) did not apply to actions taken against non-Americans outside the United States–for example, the torture of Jamadi in Abu Ghraib under CIA auspices. A soldier who tortured would still be subject to the Uniform Code of Military Justice. But under this legal theory no criminal law would apply to a CIA torturer. It was to preserve this impunity that Vice President Cheney fought to exempt the CIA from the ban on cruel, inhuman or degrading treatment proposed by Senator John McCain and passed, 90 to 9, by the Senate.

When George W. Bush was asked about torture in early November, he said: "Any activity we conduct is within the law. We do not torture." How could he say that after the hundreds of convincing reports of torture and maltreatment? One possible answer is that he has not allowed himself to know the truth. Another is that his lawyers have so gutted the law governing these matters that not much, in their view, is unlawful.

But there is another explanation for Bush's words: confidence that words can overcome reality. Just as a large part of the American people could be led to believe in nonexistent links between Saddam Hussein and the 9/11 bombers, so it could be persuaded–in the teeth of the evidence–that "we do not torture." And there is reason for that confidence.

Congress has shown no great zeal for tracking down responsibility for the abuse of detainees in Iraq, Afghanistan and Guantánamo Bay. It has reacted with the equivalent of a yawn to the disclosure of "extraordinary rendition," the shipment of prisoners to Egypt, Syria and other places where torture is common practice. The Senate, moved by the power of John McCain's example, voted for his ban on prisoner abuse. But then it approved a devastating prohibition on the use of habeas corpus by Guantánamo prisoners to test the lawfulness of their imprisonment.

The truth is that most members of Congress are scared to do anything that could be portrayed, in a campaign, as being soft on terrorists. They worry that if there is another terrorist strike in this country, any vote to hold true to the law of war or even to investigate what has happened could be held against them.

Playing cat's-paw to the Administration, Congress has turned aside all demands for an independent investigation of Abu Ghraib and the other horrors–and of the policies that led to them. When Dana Priest of the Washington Post uncovered the chain of secret CIA prisons around the world, the reaction of Republican leaders of the House and Senate was not to look into the agency's doings but to demand an investigation of the leak.

The press has provided flickering light on the torture scandal, with some notable stories but not the sustained, relentless attention of Watergate. In the daily papers the outstanding performer has been Priest, who uncovered the Justice Department memos that took such a permissive view of torture. Seymour Hersh told us about Abu Ghraib and much else in The New Yorker.

The public, as I have indicated, seemed to lose its sense of outrage once the visual evidence from Abu Ghraib faded. As in every war through American history, it looked primarily to the President to ease its anxiety. The fear aroused by September 11 did not easily dissipate.

Not one of the major actors in the torture story has been effectively called to account: not Rumsfeld, who loosened the rules on interrogation of prisoners; not Alberto Gonzales, now Attorney General, who as White House Counsel approved the torture memorandums; and not the Justice Department lawyers who wrote them.

Among those officials there is no sign of repentance. One of them has indeed become a kind of preacher of the legitimacy of using pressure on suspected terrorists. He is John Yoo, who was a lawyer in the Justice Department's Office of Legal Counsel from 2001 to 2003 and is now a professor at the law school of the University of California, Berkeley, and a visiting scholar at the American Enterprise Institute in Washington. In frequent television appearances and public forums he argues a theme of those torture memos: that President Bush as Commander in Chief is empowered by the Constitution to order what treatment he wishes for detainees in the "war on terror." His constitutional argument, that the Framers of the Constitution intended to clothe the President with the war powers of a king, conflicts with the near universal understanding of the constitutional text, with its careful balancing of executive, legislative and judicial power.

A New York lawyer who has contributed greatly to exposure of the torture phenomenon, Scott Horton, has suggested that Yoo's views echo those of a German legal thinker of the period between the world wars, Carl Schmitt. Schmitt argued that when it came to degraded enemies like the Soviet Union, the idea of complying with international law was a romantic delusion. The enemy, rather, must be seen as absolute–stripped of all legal rights.

Those who want to relax the laws against torture often make the "ticking bomb" argument: that if a prisoner may know the location of a bomb set to go off shortly, torturing him is justified to save lives. If captors believe that, they may well resort to forceful interrogation. But to write such an exception into the rules invites the systematic use of torture. I had a lesson in the danger of the ticking-bomb argument years ago in Israel. I was interviewing Jacobo Timerman, the Argentine publisher who was imprisoned and tortured by the military regime that for a time took over Argentina. (Intervention by the Carter Administration saved Timerman's life; on release from prison he immigrated to Israel.) Timerman turned the interview around and asked me questions about torture, positing the ticking-bomb situation. I tried to avoid the question, but he pressed me to answer. Finally, I said that I might authorize torture in such a situation. "No!" he shouted. "You must never start down that road."

Americans are not immune from evil; no people are. We know now that American soldiers, improperly led, can beat to death prisoners they have in their minds dehumanized. What can we do to limit the evil?

Investigation is one idea, widely endorsed. An independent body like the one that carried out the 9/11 investigation could tell us much that we do not know: not just an authoritative account of the wrongs done but a timeline of the official opinions and actions that opened the way for them. But I think a more effective solution would be the appointment of a special prosecutor. He or she would have the power not just to find the facts but to prosecute the wrongdoers. For we must not forget that not only treaties but criminal laws forbid the torture, mistreatment and humiliation of those we take in conflict.

It is unimaginable that President Bush would agree to a special prosecutor for war crimes if ever the public and Congress grew exercised enough to demand one. But you never know about history. The other day, on the sixtieth anniversary of the Nuremberg prosecution of Nazi officials, Scott Horton recalled that Nuremberg established the principle of command responsibility for abuse–and punished those who wrote legal memorandums counseling German officials to ignore the conventions protecting prisoners.

The chief American prosecutor at Nuremberg, Justice Robert H. Jackson of the Supreme Court, warned that "the record on which we judge these defendants today is the record on which history will judge us tomorrow. To pass these defendants a poisoned chalice is to put it to our lips as well."

Horton said the moment of historical reckoning for American officials may come. "A number of key Bush officials," he wrote, "are more likely to be the Pinochets of the next generation–blocked from international travel and forever fending off extradition warrants and prosecutors' questions."