Britain's Court of Appeal has upheld a decade-old policy that judges may sentence people convicted of the most serious crimes to life in prison with no possibility of parole.
The judgment comes after the European Court of Human Rights said Britain should review the policy.
It ruled last year that whole-life terms amounted to "inhuman and degrading treatment" because there was no chance the sentence could be reduced.
But five British judges led by Lord Chief Justice John Thomas said that handing out such sentences in "rare and exceptional" cases was compatible with the European Convention on Human Rights.
They also said on Tuesday that the European court had erred in saying the sentences could not be reduced, because the British government already has the power to free prisoners on compassionate grounds where there are "exceptional circumstances."
There are about 50 prisoners in Britain serving "whole-life" sentences.
The appeals court dismissed a challenge from a convicted murderer against his "excessive" sentence and ordered that another, triple killer Ian McLoughlin, have his 40-year sentence increased to life.
British Attorney-General Dominic Grieve applauded the ruling, which he said "gives the clarity our judges need."
Sentencing of the killers of British soldier Lee Rigby, who were convicted in December, was put on hold until Tuesday's court ruling.
