Britain's highest court says evidence obtained by torture cannot be introduced in British legal proceedings.
A panel of seven Law Lords has ruled that torture is an evil that never can be justified and always must be punished.
The ruling overturns a lower court decision last year that would have allowed evidence obtained by torture if it was extracted in a foreign country with no British involvement.
British Home Office Minister Beverley Hughes has welcomed the ruling. "We have never relied on evidence that could have been obtained from torture in this way," she said. "The prime minister [Tony Blair] made it crystal clear yesterday that we don't condone torture in any circumstances whatsoever."
The Law Lords' decision affects the cases of eight men who had been held without charge on national security grounds as suspected terrorist threats.
Several of the men had claimed at a special immigration commission that they were tortured at U.S.-run detention centers. Their lawyers argued that evidence obtained through torture should not be used against them.
The British ruling comes a day after the United States announced a prohibition against inhumane treatment of detainees in the custody of any American agency anywhere in the world. U.S. law prohibits the use of evidence obtained through any kind of coercion.