European judges ruled Tuesday that Britain had violated the rights of three notorious killers by sentencing them to "whole-life" prison terms, sparking fury in London.
The decision put further strain on Britain's already-difficult relationship with the European Court of Human Rights (ECHR), with Justice Secretary Chris Grayling saying the authors of Europe's rights code would be "turning in their graves" at the ruling.
Prime Minister David Cameron's office said he was also "very, very disappointed" at the decision.
"He profoundly disagrees with the court's ruling. He is a strong supporter of whole life (sentences)," Cameron's spokesman said.
The Strasbourg-based court said the sentences against Jeremy Bamber, jailed for murdering five members of his family in 1985, serial killer Peter Moore and multiple-murderer Douglas Vinter were "inhuman and degrading" because they did not include the possibility of review.
The court said the fact that "they had no hope of release" was a violation of their rights, but added that the ruling was not intended "to give the applicants any prospect of imminent release".
The three had appealed their whole-life prison sentences -- which mean they cannot be released except at the discretion of the justice secretary or on compassionate grounds -- under Article 3 of the European Convention on Human Rights, which forbids "inhuman and degrading treatment".
The case was sent to the court's Grand Chamber after the three narrowly lost their first European court hearing last year, with judges voting four to three that there had been no violation of their rights.
In its ruling released Tuesday, the Grand Chamber judges voted 16 to one that in order for life sentences to conform with European rights law "there had to be both a possibility of release and a possibility of review".
It said there was a clear precedent in European and international law for providing for reviews of life sentences after a set period, usually 25 years.
Grayling said he "profoundly" disagreed with the ruling and that it reinforced his desire to curtail the court's role in Britain.
"The British people will find this ruling intensely frustrating and hard to understand. What the court is saying is that a judge can no longer tell the most appalling criminals that they will never be released," he said.
"I think the people who wrote the original Human Rights Convention would be turning in their graves at this ruling," he said.
Bamber, 52, has been in prison since 1986 for the killings of his adoptive parents, his sister and her two young children at the family home in Essex. He has always protested his innocence, claiming that his schizophrenic sister carried out the murders before turning the gun on herself.
Moore, 66, is serving the life sentence for the murders of four gay men he stabbed to death in Wales between September and December 1995.
Vinter, 43, was convicted in 2008 of killing his wife while still on parole for a first murder, the killing of a work colleague in 1996.
Britain has long had a troubled relationship with the ECHR, with British officials slamming the court for ruling last year that terror suspect Abu Qatada could not be deported to Jordan. He was eventually deported this week after a decade-long legal battle.
Britain also has yet to implement a 2005 order from the court to lift a blanket ban on prisoners voting.
In a statement released along with Tuesday's ruling, the court sought to downplay its impact on Britain, noting that only 2.6 percent of its pending cases involve the country and that "the vast majority of cases lodged against the United Kingdom are found to be clearly inadmissible".
It said that in 2012 the court had found against Britain in only 0.6 percent of cases lodged against it.