"Suppose a terrorist has hidden an atomic bomb on Manhattan Island which will detonate at noon on July 4," wrote philosopher Michael Levin. "Suppose further that he is caught at 10 a.m. of the fateful day, but -- preferring death to failure -- won't disclose where the bomb is. What do we do? If we follow due process -- wait for his lawyer, arraign him -- millions of people will die. If the only way to save those lives is to subject the terrorist to the most excruciating possible pain, what grounds can there be for not doing it? I suggest there are none." Mr. Levin wrote this provocative passage in 1982. At the time, and for almost two decades after, the debate about whether torture may sometimes be justified was a popular exercise in moral philosophy classes but it was seldom heard anywhere else. Most people simply didn't imagine extreme situations such as Mr. Levin's ticking-bomb scenario. Torture was simply wrong. And that consensus was enshrined in the 1984 United Nations Convention Against Torture, which forbids the deliberate infliction of pain or suffering under any and all circumstances: Not even a ticking atomic bomb can legally justify torture. Then came Sept. 11, 2001. The terrorist attacks that day revealed to anyone with a television the depth of Islamist fanaticism and the terrible carnage that can be inflicted by people whose greatest desire is to kill and die. Suddenly, whether torture is always wrong was no academic exercise. The first hint of the coming debate appeared in the media shortly after Sept. 11, when anonymous FBI agents were quoted saying they may need the authority to torture to prevent another catastrophe. Not long after, Alan Dershowitz, the renowned civil libertarian and law professor at Harvard University, received widespread attention for his suggestion that the law allow for "torture warrants" to be made available in extreme situations. Many others joined in to suggest that while torture may be awful, sometimes it is just. Even Richard Posner, an esteemed judge of the U.S. federal court of appeals, wrote in The New Republic magazine, that "if the stakes are high enough, torture is permissible. No one who denies that that is the case should be in a position of responsibility." The revisionist talk even reached the various human rights bodies of the United Nations, says Malcolm Evans, a professor of international law at the University of Bristol in England. "This is deeply worrying, coming from these levels." It seemed torture was creeping toward some degree of legitimacy in Western countries where it had been firmly rejected and condemned. Human rights activists were appalled and fought back. Arguments flared up repeatedly on television, in newspapers, book reviews and intellectual magazines. Still, neither international nor domestic law has changed. Torture continues to be forbidden under any and all circumstances. Should it be? Michael Levin's imagined scenario makes the issue seem simple and clear: If a terrorist bomb is ticking and torture is the only way to save a city, it's hard not to believe we must torture. Others, thinking of the Sept. 11 attacks, would go further: If we want to stop the terrorists from obtaining that bomb in the first place -- or preparing any other deadly plots -- counter-terrorism officials should be free to torture terrorists whenever necessary. But quick conclusions would not be wise. More than two years after Sept. 11, the debate about torture has played out repeatedly, argument has been met with counter-argument, and the only thing that has become absolutely certain is that the debate is not simple and clear. Like torture itself, it is complex and troubling, no matter which side of the issue one takes. - - - Two arguments have been heard that would short-circuit the whole discussion. The first of these is the idea -- common to some schools of philosophy -- that an evil act remains evil even if it has very good consequences. Torture is always wrong and must always be forbidden, this reasoning goes, even if a particular act of torture were to save many lives. It's a view summed up in the Roman maxim, "let justice endure though the world should perish," and while that may be satisfying to some philosophers, it's not to the great majority of us who do consider the consequences of an act in deciding whether that act is right. So few people would stop the discussion here. Another attempted short-circuit is the idea that so-called "stress-and-duress" interrogation techniques -- sleep and food deprivation, constant noise, forcing prisoners into awkward positions, etc. -- could be used. This shouldn't trouble us morally, some say, because these techniques don't cause enough suffering to be "real torture," as one writer put it. This argument is simply wrong -- stress-and-duress does inflict terrible suffering and it is torture. And stress-and-duress methods take time, so they would be useless in the classic ticking-bomb scenario. The debate cannot be dodged this way. Alex Neve, secretary-general of Amnesty International Canada, suggests the starting point of the debate must be a very basic question: Does torture work? If the answer is no, after all, there's no reason to even consider using it. And Mr. Neve is certain the answer is no. "The notion that you can beat the truth out of someone in that kind of highly charged situation is false and misguided. When you start beating and torturing people they'll say anything to get the pain to stop." This objection to torture dates back to ancient times and it was a key argument in the 18th century, when the modern anti-torture movement was launched. There is literally centuries of evidence to support it, the very latest example being Maher Arar, who insists that his confession during his Syrian imprisonment was a lie he told simply to stop his captors from beating him. Similar stories are told by torture victims the world over. In an Egyptian case that recently came to light, torture caused a father to "confess" to the murder of his daughter, who later turned up alive and well. During an interrogation in Apartheid South Africa, a mixup in code names resulted in a tortured political prisoner admitting that he had murdered himself. The tendency of torture to produce false information is so well documented no one seriously disputes it, but that doesn't prove that torture never produces valid information. In a ruling that forbade the use of stress-and-duress techniques, for example, the Israeli Supreme Court accepted that some terrorist attacks had been foiled by the use of the techniques in interrogations. Alan Dershowitz says another success story is a case from the mid-1990s in which Filipino soldiers "arrested a Muslim terrorist who had on him plans, and they tortured him for 40-something days and they got him to admit there was a plan to kill the Pope and also a plan to blow up various western airliners going across the Pacific. They didn't believe him, as they should not," says Mr. Dershowitz, who agrees that torture often generates false information. Instead, the interrogators demanded the suspect provide proof of his claims or they would continue with the torture. "He led them to a tailor who was making the robe that was going to be worn by the terrorist that had pockets in it for the explosives and showed them the equipment that was going to be used to blow up the plane. When that happens, you believe it." Torture can be effective, Mr. Dershowitz says, provided interrogators always insist on corroboration. "It has to be self-proving. He has to lead you to hard evidence." Defenders of the absolute ban on torture also argue the debate is too narrowly focused, that it's not enough to say that the benefits of torture in something like a ticking-bomb scenario -- the lives saved -- outweigh the sheer inhumanity of committing torture. Any use of torture also carries the risk of hidden costs, and these have to be weighed against any alleged benefit. "Torturing radical Islamists makes them more violent," Dr. Suzan Fayed, an Egyptian psychiatrist and human rights activist told the British newspaper The Guardian. The most infamous example is that of Dr. Ayman al-Zawahiri, an Egyptian Islamist arrested and tortured following the murder of Egyptian president Anwar Sadat in 1981. Many who knew Dr. al-Zawahiri are convinced the torture radicalized his views: After his release, Dr. al-Zawahiri left for Afghanistan, where he met Osama bin Laden and ultimately became the No. 2 man in al-Qaeda. Torture can also radicalize whole peoples, as victims become "living martyrs" for their cause and their families, clans and tribes are driven into opposition. Torture can convince moderates "that the regime deserves destroying because it does not respect the dignity of people," Hafiz Abu Sa'eda, the head of the Egyptian Organization for Human Rights, told The Guardian. Many observers feel this is exactly what happened in Algeria in the 1950s and 1960s: The French military successfully used torture to crack terrorist rings, but the brutality drove the previously passive Algerian population into mass rebellion. Torture was similarly counter-productive in Turkey and Northern Ireland. "Whenever people are tortured," says Alex Neve, "that contributes to the ongoing cycles of violence and repression and grievance and revenge which fuel not only human rights violations, but lead to civil war and provide the fertile ground in which extremist groups take hold. It ultimately leads to men, women and children around the world being more insecure, not more secure." Mr. Neve argues that for a Western government to even suggest that it may use torture would inflict another major cost. "It undermines the ability of the Canadian or American government to make clear and forceful representations to any other governments that may be engaged in torture. Representations that torture must come to an end are dramatically undermined if a government has taken steps to allow torture to take place." It wouldn't matter if we were to say our use of torture would be only in extreme cases of national security, Mr. Neve insists. "Those are precisely the kinds of excuses and justifications that repressive governments around the world use to justify their misdeeds and actions. (For Western governments) to use that same language and those same excuses will simply fuel and encourage that practice elsewhere." Many fear this is already happening as a result of the published reports indicating the United States is using stress-and-duress techniques in its terrorism interrogations. An Amnesty International report called American behaviour "the threat of a bad example" and human rights activists interviewed by the Citizen in Egypt and Turkey unanimously agreed that the allegations about stress-and-duress has made it harder for them to fight torture in their countries. Still, it can be argued, an exception to the ban on torture could be narrowly crafted to avoid at least some of these "hidden" costs. And in dire emergencies, we still may decide that even the hidden costs of torture do not outweigh the terrible loss of life that will happen if we do not torture. In that case, we would still demand an exception to the ban, although it would be a very narrow exception to be used in only the most extreme emergencies, such as an atomic bomb ticking in Manhattan. Malcolm Evans says it's tempting to think such a narrow exception is possible, "but even in that ticking-bomb situation, once you accept the legitimacy of (torture), it spills out into society." This "spilling out" could happen several ways. First, there's the problem of certainty. The ticking-bomb scenario assumes the police know with absolute certainty that there is a bomb and they have the man who placed it. But, says William Aceves, a law professor at California Western School of Law in San Diego, "the problem is you probably will never find a case where you know for a fact that that bomb is there or that this person has that information." What's much more likely is a situation in which the police are fairly certain, although not 100-per-cent certain. Should they torture under those circumstances? "It becomes very easy to say, well, let's require an 80-per-cent chance that we have the right guy. That sounds reasonable. But what if it's 50 per cent? What if it's 40 per cent? What if it's five per cent? I think the reality of law enforcement is we are never sure of anything, and I think that if you justify torture at that one extreme, it becomes easy to lower the standard for when we are prepared to torture someone." Another standard that risks dropping is the potential harm required to justify torture. In Michael Levin's scenario, millions could be killed. But in the Sept. 11, 2001, attacks, the worst terrorist atrocities in history, around 3,000 died. Would torture have been justified in order to save those lives? And if 3,000, what about 300? Thirty? Three? If torture is deemed legitimate to save many lives, we may ultimately say it is legitimate to save even one life. Alan Dershowitz cites a recent, troubling case in Germany in which police arrested a man believed to have kidnapped the son of an industrialist. "The guy admitted he was the kidnapper. There was no doubt about it. He just gloated and wouldn't tell them where the boy was. And they got (illegal) authorization to torture him, and as soon as they showed him the authorization, he told them where the boy was. Unfortunately, the boy was dead. But it started a great debate in Germany as to whether or not torture is justified in order to save one innocent life." Alex Neve worries about another way that a narrow exception could spill out into something wider. "If it's OK to torture this person because you're pretty sure they know where the bomb is, does that mean that you should be able to torture the person you're pretty sure knows where to find the person you're pretty sure knows where the bomb is? "Does it mean you're allowed to torture someone from their family, because certainly they'll have some information? Does it mean you're allowed to torture all members of their political organization? Or their religious faith? Some of these possibilities may start to sound extreme, but that's exactly the pattern of human rights abuses we see around the world." Michael Levin understood that making an exception for something as extreme as a ticking bomb sets up a logic that pushes for more and more exceptions. In fact, he argued in favour of following that logic to its conclusion. "Once you concede that torture is justified in extreme cases, you have admitted that the decision to use torture is a matter of balancing innocent lives against the means needed to save them." Mr. Levin applied that calculation to less-extreme scenarios. By the end of his article, he concluded that torture should be used against the "obviously guilty" in any situation where it could save an innocent life -- even routine kidnappings. Alan Dershowitz does not support such a radical position, despite many media reports to the contrary. "I would say 90 per cent of the articles that have been written about my position have totally and completely distorted my view and made me out to be a strong supporter of torture." Mr. Dershowitz says he's not trying to resolve whether torture is morally right in some circumstances. "My position is that torture will, in fact, occur," particularly in a major crisis like a ticking-bomb scenario. "And for me, the issue is, if it's going to happen, is it worse to have it happen the way we're doing it in the United States now, surreptitiously, with deniability, in secret locations, without any approval? Or is it worse to authorize it by judicial or executive warrant, so there's accountability?" Mr. Dershowitz's "torture warrants" would only be available in true ticking-bomb crises where there was "absolute certainty, the kind of certainty that is required to execute somebody." Having clear, fixed criteria for obtaining a warrant would keep it under tight control and ensure torture wouldn't spread, Mr. Dershowitz feels. During the Middle Ages, both England and France permitted torture, Mr. Dershowitz says, "but England required a torture warrant and there was much less (torture) and it was much more subject to control. And when England decided to abolish it, it was much easier to abolish, because you just had to publish a rule saying no more warrants would be given." Richard Posner thinks Mr. Dershowitz's argument is too narrowly logical and ignores how people really behave. "If rules are promulgated permitting torture in defined circumstances," Judge Posner wrote in The New Republic, "some officials are bound to want to explore the outer bounds of the rules." Even bright lines can be stretched. Worse, wrote Judge Posner, torture warrants would legitimize torture, and one way or another, that will inevitably lead to more of it. "Having been regularized, the practice will become regular." Israeli experience suggests Judge Posner is right. In 1987, Israel authorized its General Security Service (the Shin Bet) to use what are now known as stress-and-duress techniques -- including sleep-deprivation, forced awkward positions, and "a moderate measure of physical force" -- during interrogations. Guidelines detailed methods and carefully defined when they could be used, and a high-level committee monitored compliance. The ticking-bomb scenario was constantly cited in support of this change, but despite all the safeguards, the use of these techniques rapidly proliferated so that an emergency measure became something close to routine practice. In 1999, the Israeli supreme court ruled that all the stress-and-duress techniques were illegal and their use declined. - - - It seems that defenders of the absolute ban on torture have been successful in showing that any exception to the ban would carry serious, even terrible, costs. But still they have to face the brutal scenario that began this essay. What if there is an atomic bomb ticking in Manhattan and the police know, with great certainty, they have the perpetrator under arrest? However bad the costs of torturing may be, surely, in these rare, extreme circumstances, they are outweighed by the costs of not torturing. So what should the police do? Malcolm Evans sighs when he's asked about this ultimate choice between evils. "It would be a very brave person who could actually say with complete moral certainty that if they were put in that position that they would not be prepared to (torture)," he says. "I think one simply does what one does and then throw the case to the judgement of society. What else can one do?" Under these circumstances, it's not likely a police officer would be punished for saving countless lives, writes Henry Shue, an ethicist at Cornell University who supports the absolute ban on torture. "If the situation approximates those in the imaginary examples in which torture seems possible to justify," he writes, "a judge can surely be expected to suspend the sentence." But this expectation must never be turned into an official ticking-bomb exception, argues Slavo Zizek, a Slovenian social theorist. Only by keeping the total ban "do we retain the sense of guilt, the awareness of the inadmissibility of what we have done." In its ruling forbidding stress-and-duress techniques, Israel's supreme court acknowledged the challenge of the ticking-bomb scenario, but suggested an officer charged with torture under those circumstance could claim the defence of necessity at trial. Canadian law, too, has a defence of necessity under which a person is acquitted for doing something that's normally illegal if it was necessary to save lives -- such as a mother who robs a store because she was ordered to by a kidnapper who holds her daughter. Mercy can also be granted by the federal justice minister. Whether either mechanism would clash with the absolute ban on torture under international law is unclear. But as Sanford Levinson, a law professor at the University of Texas, points out, this solution basically admits there are forms of "morally permissible torture." And if a trial actually resulted in an acquittal, a suspended sentence, or a grant of mercy, it would give "formal imprimatur" to actions that are supposedly forbidden. In other words, even this position risks legitimizing torture. "There are no happy solutions," says Alan Dershowitz, which is probably the only thing that everyone involved in this debate agrees on. "This is a choice of evils. And a choice of evils requires articulation. Bring it to the surface. That's what's important about this debate."