Killers' life terms 'breach their human rights'
The European Court of Human Rights has ruled the whole-life tariffs given to murderer Jeremy Bamber and two other killers breached their human rights.
But they said this did not mean there was "any prospect of imminent release".
Prime Minister David Cameron said he "profoundly disagrees with the court's ruling", adding he is a "strong supporter of whole-life tariffs".
On a website, Bamber, who murdered five members of his family, said the verdict was "hollow" as he was still serving a sentence for a crime he did not commit.
Bamber brought the case to the court's upper chamber, along with serial killer Peter Moore and double murderer Douglas Vinter, after losing a previous appeal.
BBC home affairs correspondent Dominic Casciani said the ruling, which applies in England and Wales, was significant both legally and politically, and it would now have to be considered by the UK government.
The government cannot appeal against this ruling but now has six months to consider its response.
'No chance to atone'
The three men are among a group of 49 people in England and Wales who are serving whole-life tariffs.
This means they cannot be released other than at the discretion of the justice secretary on compassionate grounds - for example, if they are terminally ill or seriously incapacitated.
Up until 2003, all terms could be reviewed, including whole-life tariffs after 25 years.
The men claimed that being denied any prospect of release was a violation of Article 3 of the European Convention on Human Rights - which protects people from inhuman or degrading treatment.
The court found that for a life sentence to remain compatible with the European Convention on Human Rights there had to be both a possibility of release and a possibility of review.
The judges said: "Moreover, if such a prisoner is incarcerated without any prospect of release and without the possibility of having his life sentence reviewed, there is the risk that he can never atone for his offence: whatever the prisoner does in prison, however exceptional his progress towards rehabilitation, his punishment remains fixed and unreviewable.
"If anything, the punishment becomes greater with time: the longer the prisoner lives, the longer his sentence."
The judges said the current UK law concerning the justice secretary's power to release a whole-life prisoner was "unclear".
They said: "Given this lack of clarity and the absence of a dedicated review mechanism for whole-life orders, the Court was not persuaded that, at the present time, the applicants' life sentences were compatible with Article 3."
The judges said it was up to the national authorities to decide when such a review should take place.
"This being said, the Court would also observe that the comparative and international law materials before it show clear support for the institution of a dedicated mechanism guaranteeing a review no later than 25 years after the imposition of a life sentence, with further periodic reviews thereafter," the ruling said.
The question of whether the three men should be detained because they are a danger to the public was not considered as part of this ruling.
Justice Secretary Chris Grayling said: "I don't believe that the people who wrote that convention ever imagined that it would stop a judge saying to a really evil offender - 'you'll spend the rest of your life behind bars'.
"It reaffirms, to me, my own determination to bring real changes to our human rights laws and to see a real curtailing of the role of the European Court in this country."
Former Labour home secretary David Blunkett said his government changed the law in 2003 "so that life really meant life when sentencing those who had committed the most heinous crimes".
"Whatever the technical justification the Strasbourg court may have, it is the right of the British Parliament to determine the sentence of those who have committed such crimes..." he said.
"To do otherwise can only lead to disillusionment, mistrust of, and a dangerous alienation from, our democracy itself."
'Get out of jail free'
Bamber was jailed for the five murders in Essex in 1985.
He has always protested his innocence and claims his schizophrenic sister Sheila Caffell shot her family before turning the gun on herself.
In a statement which appeared on his blog, which is part of the Jeremy Bamber Campaign website, he said: "Reviews and parole hearings are subject to a risk assessment to gauge dangerousness and this is influenced by the inmate's confession, remorse and rehabilitation for reintegration back into the community.
"In my case I do not fit the criteria for parole on this basis."
Moore killed four gay men for his sexual gratification in north Wales in 1995.
In 2008, Vinter, from Middlesbrough, admitted killing his wife Anne White. He had been released from prison in 2005 after serving nine years for murdering a colleague.
Vinter's solicitor, Simon Creighton, said the ruling could not be used as a "get out of jail free" excuse for life-term prisoners.
"It's very important that the court has recognised that no sentence should be once and for all and there should always be some right to look at some sentences again in the future," he said.
"They have not said that anyone must be released, what they have said is that it must be reviewed."
The Strasbourg court ruling only applies in England and Wales. In Scotland, there is no provision for a whole-life tariff, while prisoners given such a sentence in Northern Ireland may already have their cases reviewed.