The abuse of Iraqi prisoners has provoked international outrage. It raises the question what kind of interrogation, if any, is acceptable under modern international law?
By Duncan Walker
BBC News Online Magazine
Unpublished photos of the abuse of Iraqi prisoners have been shown behind closed doors to US Senators, some of whom describe the images as "disgusting".
It follows revulsion at shots including a grinning female officer by naked Iraqis, dogs straining at the leash as a prisoner cowers and a hooded man on a box with wires attached to him - all of which were reproduced in the world's media.
Lynndie England, the 21-year-old at the centre of the controversy and one of seven US soldiers charged with abuse, says she was ordered to carry out the acts as preparation for the questioning of prisoners.
British forces in Iraq have also been accused of abuse, and
Defence Secretary Geoff Hoon admitted the hooding of prisoners - a practice banned by the Army in the 1970s - was only stopped in Iraq last year.
But if such actions are unacceptable, what techniques can be legitimately used by interrogators?
After all, in some cases it could be that information obtained quickly from prisoners may be extremely valuable and even life-saving.
Under the terms of the United Nations Convention Against Torture, to which the UK and US are signatories, there are strict guidelines which must be adhered to - no matter who the prisoner is, or what you think they may know.
It explicitly prohibits the intentional use of physical or mental pain or suffering as a means of obtaining a confession, or other information.
Duncan March, a former Royal Marine who has served in Northern Ireland and Iraq, says the rules mean you can do little more than ask prisoners questions, including their name, rank and number.
But there are a number of interrogation techniques which fall short of the standards set by the convention, which he advises the civilian clients he now trains to be aware of in case they are taken hostage.
Among them, psychological techniques are most important. "People are like a piano, you just need to know which key to press," he says.
Interrogators may try to find out about a person's sexuality, their family, their religion and attitude and use it against them.
In contrast, Mr March says, physical abuse is not an effective way of breaking a prisoner down. "It gets to the point where if a human being is beaten you don't get anything from them."
Techniques such as hooding, sleep deprivation and the use of white noise can all disorientate a prisoner.
"It could be you come out of isolation and just want to talk to someone. You're working with them emotionally."
Although he has no evidence to support his belief, he suspects such techniques are likely to have been used against Saddam Hussein. US authorities say the former Iraqi leader is being held according to the terms of the Geneva Convention.
Pictures of abuse prompted outrage (Photo courtesy of The New Yorker)
Former British Army special forces officer Hugh McManners, writing in the Independent newspaper, also suggests that the rules may sometimes be stretched.
"In between interrogation sessions, candidates might be held in isolation, which could include being hooded, blanked off from the rest of the world by white noise, and then 'stressed' by being made to spread-eagle against a wall, followed by sitting cross-legged on the floor with hands on head," he said.
Both Mr March and Mr McManners suggest time can be a critical factor and professional interrogators can obtain information that can be of great value to troops.
On Thursday, the New York Times reported that CIA agents use harsh interrogation methods for dealing with top al-Qaeda members.
It says one was disciplined for threatening a prisoner with a gun, and that interrogators used a technique known as "water boarding" in which a prisoner is strapped down, pushed under water and allowed to think they may drown.
Last week human rights organisation Amnesty International
sent an open letter to George Bush, protesting against the use of degrading treatment and punishment.
Amnesty quoted a US major as saying that while physical contact between interrogator and detainees is prohibited, "sleep deprivation and stress positions and all that could be used. But they must be authorized".
Any suggestion that distressing interrogation techniques can be legitimately used - even against the likes of Saddam Hussein or al-Qaeda leaders, is dismissed by Sir Nigel Rodley, chair of the Human Rights Centre at the University of Essex.
He says the conditions set out by the UN Convention Against Torture are unambiguous and not to be broken lightly. "When it gets to the point of degrading or inflicting severe mental or physical pain, then it's illegal," says Sir Nigel.
He suggests, however, that there are some occasions when otherwise contentious actions may not fall under the convention.
"A lot has to do with how it's happening. Hooding someone for transferring them from point A to point B so they can't get important information about where they're taken to could be a necessary security measure.
"But if it's being used to scare the living daylights out of them then it's not acceptable."
For the British Army at least the issue of interrogation methods came to head as long ago as the 1970s.
"Sensory deprivation" including isolation, white noise, hooding, sleep deprivation and physical hardship were used to break down a prisoner's resistance before and during interrogation.
The practice was ended following an outcry over the treatment of IRA suspects held without trial.
Lynndie England says she was acting under orders
Amnesty International's Claudio Cordone says the organisation believes the use of torture, or harsh questioning techniques is much less common than people may think. But there are still legitimate options for interrogators.
"People can be interrogated in a sustained way if tactics are used like pretending someone else has confessed," he says.
"That, per se, would not break international law so long as it's not a threat."
Mr Cordone says the abuse and torture of prisoners may seem like a necessary option at times, particularly in the midst of a conflict, but countries have to make choices about their values.
"In certain circumstances torture works - we're not going to deny that. But it happens much more rarely than people think and the cost to yourself, and to people you torture, are such that it does not pay."