Murderers who commit the most "heinous" of crimes can be sent to prison for the rest of their lives, leading judges have ruled.
A specially-constituted court declared that sentencing judges can continue to impose "whole-life" tariffs in such cases.
Sentencing in a number of high-profile criminal cases had been put on hold - including the terms to be handed out to Fusilier Lee Rigby's murderers Michael Adebolajo and Michael Adebowale - pending the Court of Appeal's findings.
Backing the use of "life-means-life" orders, a panel of five judges at the Court of Appeal increased the "unduly lenient" 40-year minimum being served by killer Ian McLoughlin, who murdered a man while on day release, to a whole-life term.
And they dismissed a challenge by Lee Newell, who murdered a child killer while in prison, against an order imposed in his case that he can never be released.
Today's guidance from the appeal judges in London comes in the wake of a decision by the European Court of Human Rights last year in an appeal by three murderers.
Giving the panel's ruling, Lord Thomas said the court had held that the statutory scheme enacted by Parliament which enabled judges to pass whole-life orders was "entirely compatible" with the European Convention on Human Rights.
"Judges should therefore continue as they have done to impose whole-life orders in those rare and exceptional cases which fall within the statutory scheme.
"Under the statutory scheme as enacted by Parliament, the Secretary of State has power to release a prisoner on licence if he is satisfied that exceptional circumstances exist which justify the prisoner's release on compassionate grounds."
After the ruling, Attorney General Dominic Grieve, who referred the McLoughlin sentence to the court for review, said: "I am pleased that the Court of Appeal has today confirmed that those who commit the most heinous crimes can be sent to prison for the rest of their lives " As someone who has killed three times, Ian McLoughlin committed just such a crime, and following today's judgment he has received the sentence that crime required.
"I asked the Court of Appeal to look again at McLoughlin's original sentence because I did not think that the European Court of Human Rights had said anything which prevented our courts from handing down whole life terms in the most serious cases.
"The Court of Appeal has agreed with me and today's judgment gives the clarity our judges need when they are considering sentencing cases like this in the future."