By Matthew Davis
BBC News, Washington
Controversy over America's treatment of captured terror suspects is an open wound that refuses to heal.
Even techniques considered humane, have the capacity to shock and outrage
In recent days there has been international uproar at reports that the CIA set up so-called "black sites" in eastern Europe and Asia to hold suspected terrorists far from public scrutiny.
Fresh allegations of abuse by US forces have come from former Iraqi prisoners who say they were beaten, deprived of sleep, given electric shocks, shot with rubber bullets and threatened with mock executions.
Meanwhile, the US Senate has voted to restrict Guantanamo detainees' access to the US court system, just as President George W Bush is threatening to veto a proposal to ban the abuse of prisoners held abroad.
The greatest concern is the untold damage being done in the battle for hearts and minds - a major front in the US war on terror.
The debate cuts to the heart of the complexities of the war on terror - and the compromises made waging it
Memories are still fresh of the rioting that took place in Afghanistan, Pakistan and elsewhere following the publication of a since-retracted report about desecration of the Koran at Guantanamo Bay.
Images of abuse at Iraq's Abu Ghraib jail have effectively been recruitment posters for al-Qaeda.
And there are fears that dissension on how the US treats captured terrorists is making it harder to build the diplomatic, political and military alliances necessary to fight the war on terror effectively.
Terror and torture
Republican Senator John McCain was tortured during captivity in the Vietnam War.
Republican Senator John McCain was tortured during captivity in Vietnam
He says American prisoners took "great strength from the belief that we were different from our enemies... that we, if the roles were reversed, would not disgrace ourselves by committing or approving such mistreatment of them".
Senator McCain wants the US to adopt a measure banning all inhumane treatment of detainees, a proposal that has set him against the White House, which wants an exemption for the CIA.
The debate cuts to the heart of the complexities of the war on terror - and the compromises made in waging it.
President Bush is balancing his obligation to protect the American people by acquiring the kind of intelligence that can prevent terrorist attacks, with his commitment that "we do not torture" to get it.
The military says captured combatants are trained to resist US interrogation methods and it may be better for them to be unsure just how far their captors are willing to go.
Thus a new Pentagon Detainee Interrogation Policy released this month says all interrogations must be carried out humanely, in accordance with the law - but reserves the right for the US defence secretary to override this.
Accusations of ill-treatment are easy to make, and their effects hard to erase from the public consciousness even if found to be untrue.
Even strategies considered humane by the standards of a war zone have the capacity to cause shock and outrage.
Yet there is no doubt lines have been crossed - and that there is still latitude for abuse, even if it stops short of "torture".
Survival, Evasion, Resistance, Escape
Critics say America's leaders effectively lost the plot after the 9/11 attacks, and have failed to put adequate policies in place to stop abuse.
Allegations of abuse are taking a toll on America's image abroad
Jonathan H. Marks, a barrister and a bioethics fellow at Georgetown University, says that in the wake of the terror strikes there was a "visceral appeal" to a policy of hard-edged interrogation - even if such techniques are not thought to be effective.
Mr Marks says there is evidence that the US turned to a classified program designed to train US soldiers to resist abuse in enemy custody (SERE - Survival, Evasion, Resistance, Escape), to refine interrogation methods that targeted prisoners' vulnerabilities.
"The SERE model's embrace by the Pentagon's civilian leaders is further evidence that abuse tantamount to torture was national policy, not merely the product of rogue freelancers," Mr Marks says.
The American public's view on the use of torture does not seem clear-cut. The latest Newsweek opinion poll found that 58% would support torture to thwart a terrorist attack.
But the same survey showed that 51% believe it is rarely or never justified, while 44% said torture is often or sometimes justified to obtain important information.
'No brief for terrorists'
It is not only the treatment of prisoners in custody that has angered opponents.
Human rights groups have complained that US prisoners are sometimes detained arbitrarily, and kept for months on end without facing charges or trial.
The United Nations says the US-led military force in Iraq is detaining people faster than a new board can review their cases to determine whether their rights are being respected.
The US is also under increasing international pressure to answer allegations that the CIA is operating secret prisons abroad.
Senator McCain says he holds no brief for terrorists, but told American television: "It's not about them. It's about us.
"This battle we're in is about the things we stand for and believe in and practice. And that is an observance
of human rights, no matter how terrible our adversaries may be."