By Vanessa Buschschluter
The executive order signals a sharp break with the Bush Administration
In one of his first moves after taking office, US President Barack Obama signed an order banning harsh interrogation techniques used since 9/11, which critics have denounced as torture.
One of those critics is Mr Obama's nominee for the post of attorney general, Eric Holder, who has condemned the practice of waterboarding, a technique which creates the sensation of drowning.
"If you look at the history of the use of that technique, we prosecuted our own soldiers for using it in Vietnam," he told a Senate hearing. "Waterboarding is torture."
Mr Obama's executive order sets out to "promote the safe, lawful, and humane treatment of individuals in United States custody".
It bans the use of any interrogation technique not listed in the US Army's field manual, which was revised in 2006 after the scandal over mistreatment of detainees at Abu Ghraib in Iraq.
The abuses at Abu Ghraib went beyond anything permitted even in the previous version of the field manual - though many of the measures had been approved for use by the CIA in Guantanamo.
US ARMY FIELD MANUAL
Bans the following actions in intelligence operations:
Forcing the detainee to be naked, perform sexual acts, or pose in a sexual manner
Placing hoods or sacks over the head of the detainee
Placing duct tape over the eyes
Applying beatings, electric shock, burns or other forms of physical pain
Using military working dogs to threaten the detainees
Inducing injury through cold or heat
Conducting mock executions
Depriving the detainee of necessary food, water, or medical care
Denigrating the detainee's religious symbols
The CIA has until now been using its own undisclosed set of rules, but its hands will be tied by the new executive order.
Apart from waterboarding, the 2006 field manual explicitly prohibits threats, coercion, and physical abuse.
Techniques it does allow include:
Good cop, bad cop (known in the US as Mutt and Jeff):
where two interrogators take apparently opposing approaches to the subject to make the detainee identify with one of the interrogators and thereby establish rapport and co-operation
where the interrogator tries to confuse the detainee and produce contradictions which can be challenged
We Know All:
where the interrogator pretends merely to be confirming details of a story he knows already
where flattery is used to produce a bond
where the detainee's ego is attacked in the hope that he will reveal information to justify his actions
where a pre-existing fear is identified, linking its elimination to co-operation on part of the detainee
: where the interrogator says nothing to the detainee but looks him squarely in the eyes, preferably with a slight smile on his face
Former president George W Bush always denied that his country practised torture and pointed to the convictions of 11 US soldiers for the Abu Ghraib abuses.
He said the US followed the rules laid down in the UN Convention against Torture, which bans "any act by which severe pain or suffering, whether physical or mental, is intentionally inflicted on a person..."
However, in March 2008 he vetoed legislation which would have forced the CIA to adopt the army field manual. Explaining his opposition he said: "The best source of information about terrorist attacks are the terrorist themselves."
"If we were to shut down this programme and restrict the CIA to methods in the Field Manual, we could lose vital information from senior al-Qaeda terrorists, and that could cost American lives," he said.
Mr Obama laid out his position in his inaugural address.
"We reject as false the choice between our safety and our ideals," he said.
The effectiveness of coercive methods in eliciting information from detainees is hotly debated.
Outgoing CIA Director Michael Hayden has offered a strong defence of his agency's techniques.
"You can't say it didn't work. It worked," he said in a farewell news conference on 15 January.
"I am convinced the programme got the maximum amount of information, particularly out of that first generation of detainees."
Referring to top al-Qaeda suspects who were subjected to harsh interrogation techniques he said: "The Abu Zubaydahs, the Khaled Sheikh Mohammeds, I just can't conceive of any other way, given their character, given their commitment to what it is they do."
And John Kiriakou, a former CIA agent who says he took part in the interrogation of Abu Zubaydah, says that when waterboarded, Mr Zubaydah revealed information which led to the disruption of a number of terrorist attacks.
Abu Zubaydah himself later said he had made the information up.
Robert Coulam, a research professor at the Simmons School for Health Studies in Boston, says there is little systematic knowledge available to tell what works in interrogation.
President Obama has got it just about perfect. The army field manual is a very decent set of rules
Prof Philip Heyman, former US deputy attorney general
"The question is whether other interrogation approaches are available. Would a more skilful interrogator be able to elicit the same information without resorting to coercion?"
He also says that "quite apart from legal and moral issues, coercion in the hands of people who are unskilled can be very counterproductive.
"By not having highly skilled, emotionally mature interrogators, it's likely to be used in the wrong way, or applied when not needed."
The army field manual, too, warns of the negative effects of coercion, calling it a "poor technique that yields unreliable results, may damage subsequent collection efforts, and can induce the source to say what he thinks the Humint (Human Intelligence) collector wants to hear."
Rear Admiral Don Guter, who served as the US Navy's judge advocate general from 2000 to 2002, says "most interrogators will tell you that if detainees aren't treated well during their captivity, it makes their jobs much more difficult".
While misinformation and misdirection are fair game, he says, "the golden rule is that if we would not want a technique applied to our service members, we don't apply it to the detainees".
Earlier this month, the official who oversees the special military courts in Guantanamo Bay, Susan Jay Crawford, said that the interrogation of an inmate there had reached the level of torture even though he was not subjected to waterboarding.
Ms Crawford said Mohammad al-Qahtani had been interrogated for 18 to 20 hours a day almost continuously for eight weeks.
According to leaked documents, he was left in stress positions, very cold environments and was sexually humiliated - methods which, according to the Pentagon, were legal under the army field manual in force when the interrogation took place in 2002.
In an interview with the Washington Post, Ms Crawford said all charges against Mr Qahtani had been dropped, because of the methods used.
Philippe Sands, Professor of International Law at University College London, says Susan Crawford's statement is important on two levels.
"Not only is it the first time a senior Bush administration official has publicly admitted that one of the inmates held at Guantanamo was tortured," he says, "but it also shows that the material obtained by torture can't be used in court.
"So what's the purpose of harsh interrogation techniques?"
Harvard law professor Philip Heyman, who served as deputy attorney general in the Clinton administration, says that proponents of coercive interrogation techniques often use the ticking bomb example.
There's a legitimate argument that the CIA should have more leeway than the army
Benjamin Wittes, author of "Law and the Long War"
"I think many people would, if you actually had a small atomic bomb in a major US city, want to apply different interrogation rules than normal. That's been the argument the Bush administration has used," he says.
"But it's vastly different from the one we've been engaged in."
He says cases where a guilty suspect who has information that is urgently needed to save lives can be identified, and where there is no other covert or overt way of obtaining that information in time, are very unlikely.
He argues that those cases should have nothing to do with setting the general rule for interrogation.
In his view, the 2006 army field manual is "a very decent set of rules".
When our government changes its law or policy, we will follow that direction without exception, carve-out, or loophole
Michael Hayden, outgoing CIA Director
However, Benjamin Wittes, a senior fellow in Governance Studies at The Brookings Institution and author of Law and the Long War: The Future of Justice in the Age of Terror, has some reservations.
He says the idea that CIA agents should be subjected to the same set of rules as the military will not work in the long term.
"There's a legitimate argument that the CIA should have more leeway than the army. The CIA deals with a tiny number of detainees, which by definition are the most dangerous ones," he says.
"The army field manual comes nowhere near the legal line of what you can do in an interrogation and therefore ties the hands of CIA interrogators unnecessarily."
But Rear Admiral Guter argues that "it can't be the policy of the US to have more than one interrogation regime."
"We need clarity, so that anyone who is on the battlefield knows how they are supposed to treat detainees," he stresses.
Outgoing CIA director Michael Hayden has already instructed his staff to abide by the new rules.
In one of his last messages to his staff before he is replaced by Leon Panetta next month, he said the agency had many counter-terror tools in its arsenal and would adapt accordingly.
He added: "When our government changes its law or policy, we will follow that direction without exception, carve-out, or loophole."