Whole-life sentences are not "manifestly excessive or wrong in principle", leading judges at the Court of Appeal heard today.
The submission was made by a QC appearing on behalf of Attorney General Dominic Grieve, as two killers who are challenging orders that they must remain behind bars for the rest of their lives followed the proceedings via video-link from jail.
James Eadie told a panel of five judges in London, headed by the Lord Chief Justice Lord Thomas, that if a sentencing court "is of the opinion that, because of the seriousness of the offending, a minimum term should not be fixed, the court must impose a whole-life order".
In written argument before the court, Mr Eadie submitted: "The failure to impose a whole-life order in circumstances where the seriousness of the offending requires its imposition renders the sentence imposed unduly lenient".
Mr Grieve has referred the case of Ian McLoughlin to the appeal judges to consider whether a tariff of 40 years imposed in his case for murdering a man when on day release can be regarded as "unduly lenient" and should be increased.
The court is also being asked to rule on sentence challenges by Lee Newell, who murdered child killer Subhan Anwar in prison, and murderer and rapist Matthew Thomas.
The central legal issue at the hearing is the nature of the sentencing scheme for whole-life orders and the compatibility of such an order with the European Convention on Human Rights.
The Government has said that whole-life tariffs are "wholly justified in the most heinous cases".
Such terms were deemed a breach of human rights following a successful appeal to the European Court of Human Rights (ECHR) by murderers Jeremy Bamber, Douglas Vinter and Peter Moore.
Last year the trio won a ruling that their whole-life sentences amount to "inhuman and degrading treatment".
Whole-lifers should be entitled to a review of their sentence 25 years into their term at the very latest, the Grand Chamber of the Strasbourg-based court said.
The ruling by 17 judges from across Europe sparked further outrage among critics of the court - despite reassurances that the decision did not amount to grounds for imminent release.
Newell, now 45, is challenging a whole-life sentence imposed last September at Warwick Crown Court.
He was convicted alongside Gary Smith for the February 2013 murder of convicted child killer Anwar in his cell at Long Lartin Prison, Worcestershire. Newell was already serving a life sentence for a previous murder committed in 1988.
Convicted rapist Thomas was told "life means life" after murdering a newly-wed bride and then kidnapping and raping a second woman.
Thomas, now 53, from Luton, pleaded guilty in 2004 to the murder of Colette Magee. He also admitted two counts of rape, one of indecent assault and one count of kidnap of the second woman.
Triple killer McLoughlin, 55, was jailed for life at the Old Bailey last October for stabbing a man on his first day-release from prison after 21 years in custody.
When sentencing McLoughlin, the trial judge imposed a 40-year tariff, saying he could not pass a whole-life term because of the European court ruling.
McLoughlin - who had killed twice before - stabbed Graham Buck, 66, as he came to the aid of a neighbour in Little Gaddesden, Hertfordshire, last July
Those currently serving whole-life terms in England and Wales include Moors Murderer Ian Brady, who tortured and murdered children along with accomplice Myra Hindley, and serial killer Rosemary West.
The appeal judges were expected to deal with a challenge by Mark Bridger, who was convicted of the murder of five-year-old April Jones, but he abandoned his application for permission to appeal against his whole-life tariff.
Lord Thomas, sitting with Sir Brian Leveson, Lady Justice Hallett, Lord Justice Treacy and Mr Justice Burnett.The judges are expected to reserve their decision.