Britain's highest court thrust itself into the middle of a roiling international debate on Thursday, declaring that evidence obtained through torture -- no matter by whom -- was not admissible in British courts.
It also said Britain had a "positive obligation" to uphold anti-torture principles abroad as well as at home.
"The issue is one of constitutional principle, whether evidence obtained by torturing another human being may lawfully be admitted against a party to proceedings in a British court, irrespective of where, or by whom, or on whose authority the torture was inflicted," said Lord Bingham, writing the lead opinion in a unanimous ruling for the Law Lords.
"To that question I would give a very clear negative answer," he said.
The ruling dealt specifically with 10 men who were detained after the attacks on the US on Sept. 11, 2001, and were held without charge in Britain on suspicion of being terrorists.
But while the question at hand concerned only British courts, the ruling seems to have been made with the current international situation very much in mind. Several of the concurring opinions referred explicitly, and not flatteringly, to the US.
Speaking of what he said was England's justifiable pride in its common-law rejection, centuries ago, of torture as a means to an end, Lord Hoffman brought his argument forward to the current era.
"In our own century," he wrote, "many people in the United States, heirs to that common-law tradition, have felt their country dishonored by its use of torture outside the jurisdiction, and its practice of extra-legal `rendition' of suspects to countries where they would be tortured."
The 10 men are known informally as the Belmarsh detainees, after the prison where many of them were held. The case against them has been long, complicated and thick with secrecy.
But the issue of torture came up as a result of the detainees' appeals to the Special Immigration Appeals Commission, which asserted its right to consider evidence that may have been obtained under torture in other countries.
Last year, the Court of Appeal ruled that such evidence was admissible and that the government had no obligation to investigate how suspect evidence had been gathered.
Human-rights groups applauded the ruling as a landmark that set a civilized standard for evidence in terror cases.
"The Law Lords' ruling has overturned the tacit belief that torture can be condoned under certain circumstances," Amnesty International said in a statement.
"This ruling shreds any vestige of legality with which the UK government had attempted to defend a completely unlawful and reprehensible policy, introduced as part of its counterterrorism measures," it said.
US Secretary of State Condoleezza Rice, in Europe this week, has been trying to answer charges that the US routinely practices so-called extraordinary rendition, sending terror detainees abroad to places where they face possible torture.
It is unclear what practical or immediate effect the Lords' ruling overturning the Court of Appeal's decision will have.
Rights groups that had brought the case said the ruling would force the government to do three things: re-evaluate any pending or future terrorism cases to determine whether evidence had been extracted by torture; stop seeking to deport terror suspects to countries where they might be tortured; investigate possible complicity in the US policy of rendition.