Politicians, Mr Blunkett, should not set sentences in individual cases

The sentencing of criminals demonised by the press is the subject of a simple confusion. So it is well to be clear about the respective roles of politicians and judges in deciding how long people should stay in jail before today's decision by the House of Lords.

The law lords will give their ruling on a case brought by a murderer who claimed the Home Secretary violated his human rights by increasing his minimum sentence from 15 to 20 years.

The law lords should rule that it is wrong in principle that a politician should have the power to vary the sentence served by a particular individual. In doing so, however, they will be vilified by some, who will accuse them of being soft on murderers and paedophiles, and of defying democratic values as represented in the person of David Blunkett.

Mr Blunkett, meanwhile, has launched a pre-emptive strike by announcing – through official channels, in this case the News of the World – that Roy Whiting, the murderer of eight-year-old Sarah Payne, must serve a minimum 50 years of his life sentence.

Before the law lords begin to receive hate mail for correctly interpreting the Human Rights Act, therefore, we should clear up the confusion. Politicians should make law for general cases, while judges and juries should decide how that law should be applied in specific cases – and judges should then decide the sentence for those convicted, on the facts of each case.

Politicians must lay down what sentences should be available – and it is better if they allow some flexibility. Look at the trouble caused by the requirement that judges impose a life sentence for murder, regardless of the circumstances. The same hardliners who insist on life for murder are the very people who are most outraged by cases such as that of Tony Martin, the eccentric who shot a burglar.

All the same, it is open to the Home Secretary, if endorsed by a majority in Parliament, to set minimum or maximum terms, and – just as important – to set out rules for granting remission for good behaviour or for parole.

But, within the discretion allowed by politicians, the sentence itself must be decided by an independent judiciary. Without that fundamental safeguard, a state can lapse into oppression, with sentences decided by politicians for political reasons.

Those political reasons can include the desire to impress the punitive instincts of much of the public. This is not wholly ignoble. It is reasonable and democratic, even if The Independent believes it undesirable, for popular revulsion at certain crimes to be expressed in long jail sentences. But this should apply to classes of crime, not individual cases. Sentences should be set by calm deliberation on the facts of the case, not by a hue and cry whipped along by parts of the press.

Thus, in the difficult case of paedophilia, we support something like 50-year minimum terms for the very small number of persistent predatory offenders who abduct young children. But such exceptional sentences should be set by a judicial process, not by the Home Secretary at his discretion.

In other cases, such as that of Myra Hindley, who died earlier this month before today's ruling by the Lords could free her, the likelihood that she would still be a danger to anyone was remote.

In those cases, the Prison Service and the courts should have the power to vary the length of sentences under laws laid down by Parliament according to the severity of the offence and the likelihood of reoffending. The Home Secretary should not be involved.