By Paul Reynolds
World Affairs Correspondent, BBC News website
The Supreme Court is to rule on a detainee at Guantanamo
The Attorney General Lord Goldsmith's speech calling for the closure of the Guantanamo Bay camp is a significant shift by the British government, America's close ally in the "war on terror" declared by President Bush after the attacks of 11 September 2001.
Comments by the Prime Minister Tony Blair in March that it would be better if the camp were closed have now been overtaken by this clear statement that it is "unacceptable".
It might be seen as a response to the urging of the Foreign Affairs Committee which stated: "We recommend
that the Government make loud and public its objections to the existence of
such a prison regime."
There appears to have been a division of opinion within the government about how hard to press the issue.
Recently the then Defence Secretary John Reid gave a speech at the same venue, the Royal United Services Institute, where Lord Goldsmith spoke, hinting that the way to end the "anomaly" was to change international law by allowing the detention without trial of terrorist suspects.
If this were accepted, he suggested, there would be no "anomaly".
He made a defence of the thinking behind Guantanamo Bay and did not make any kind of "loud and public" objection.
Dr Reid has now left the defence ministry to become Home Secretary, where there are also issues of how liberty should be curtailed in the interests of public safety.
The issue for Lord Goldsmith has been that of fair trial. It is the basis of his objection to the camp.
He always opposed the military tribunals proposed by the United States and has now come out openly against the camp as whole because of this principle.
He said: "There are certain principles on which there can be no compromise. Fair trial is one of those - which is the reason we in the UK were unable to accept that the US military tribunals proposed for those detained at Guantanamo Bay offered sufficient guarantees of a fair trial in accordance with international standards."
He went on: "The existence of Guantanamo Bay remains unacceptable. It is time, in my view, that it should close.
"Not only would it, in my personal opinion, be right to close Guantanamo as a matter of principle, I believe it would also help to remove what has become a symbol to many - right or wrong - of injustice.
"The historic tradition of the United States as a beacon of freedom, liberty and of justice deserves the removal of this symbol."
That last bit is soft-soaping the United States, a tip of the hat common when someone criticises a government, but it does not hide his strong stand on principle.
The only question is why, if this is such a issue of principle, he has not come out with this clear line before.
The answer is that there is a growing boldness to criticise the camp.
Even Tony Blair suggested that it was not acceptable indefinitely.
And President Bush, in a recent interview said that he would like the camp to "end" at some stage, though he did not say exactly when.
He said he was waiting for a ruling by the US Supreme Court on the legality of the tribunals.
Whether the apparent desire to close the camp will turn into a decision to do so remains to be seen.
Much depends on the Supreme Court, which will rule this summer in the case of Salim Ahmed Hamdan, Osama bin Laden's driver.
Lord Goldsmith said the camp had become a symbol of injustice
He was accused in front of a military tribunal of carrying weapons for Osama bin Laden.
The case was suspended when a judge ruled that it might be illegal but this was then overruled by an appeals court in which Judge John Roberts, now the Supreme Court Chief Justice, took part.
He has withdrawn from sitting in judgment in the Supreme Court itself which has held oral hearings and whose decision is expected in June.
If the court rules that the tribunals are legal, then the camp will go through the cases of several hundred detainees who have been declared "enemy combatants".
But if it rules they are illegal, then some system of trial will have to be instituted and the nature of the camp will change.
Despite his criticism of the US over Guantanamo, Lord Goldsmith defended the British system of imposing control orders on foreign terrorists suspects it is unable to deport for fear of them being tortured abroad.
In April a High Cort judge ruled that they provided only a "thin veneer of legality" because a review of cases by a judge did not meet the fair hearing requirements of human rights legislation. The government is appealing.