'The day he was sentenced, I knew he was going to die. You don't get a death sentence for murder. Why should a child get one for robbery?' The speaker is Yvonne Scholes, whose son, Joseph, hanged himself in Stoke Heath Young Offender Institution on 24 March, barely a month after his sixteenth birthday. He had been at the prison, near Market Drayton in Shropshire, for just nine days.

Twelve years ago, the suicide of Philip Knight in a cell at Cardiff triggered a national campaign to limit the jailing of teenagers. The death of Knight - who was a few weeks younger than Scholes - became the subject of hundreds of newspaper column inches, troubled sermons by columnists, and an hour-long ITV documentary, shown at the 9pm prime time peak. Visibly concerned at the risks of incarcerating vulnerable children, the then Tory Home Secretary, David Waddington, announced that solving the problem of suicides by teenage prisoners was his 'top priority', and promised to end the practice of remanding juveniles in prison before trial.

How the agenda has changed. To date, Scholes's death has attracted a single, brief report in The Guardian . Although he was the third juvenile to take his life in jail in just over a year, Waddington's Labour successor, David Blunkett, is happily trumpeting plans which will see more young teenagers in Prison Service custody than ever before. 'We are sending out a clear warning to youngsters who think that they are above the law - you will be caught and you will be punished,' he told a conference on youth crime last month. New powers to remand juveniles would finally deal with criminal youths 'who believe that their age makes them untouchable'.

Scholes had a double misfortune: not only was he young, he had been convicted of street robbery, the offence for which the Lord Chief Justice, Lord Woolf, has told judges demands a custodial sentence 'irrespective of the age of the offender and irrespective of whether the offender has previous convictions'. Increasing sentences on two young muggers in the Court of Appeal, Woolf said that for those who stole mobile phones and other items in street robberies, jail would be 'the only option' except in 'wholly exceptional' circumstances, with a tariff of 18 months to three years even in cases where there had been no violence.

The Manchester Crown Court judge who gave Scholes two years waited 19 days after Scholes pleaded guilty before passing sentence: time enough to read his case file carefully. The following is some of what he will have learnt.

Joseph Scholes had one previous conviction - for affray. Just the sort of thing a 'young thug' might get up to, except that in his case, it arose from a fight he had with ambulance staff when, crazed and disorientated, he tried to kill himself at the end of November 2001 by taking an overdose and jumping from a window. Since his parents' acrimonious divorce some years earlier, he had allegedly suffered repeated and severe sexual abuse by a member of his father's family, and a custody battle had been fought out in court. He had been seeing a psychiatrist for months and been prescribed Prozac and other medication.

As for the three offences which he admitted, his role, said the victims and other witnesses, was peripheral. In December, following his suicide attempt and ambulance affray, he was taken into 'voluntary care' at a children's home in Sale, Greater Manchester. His arrest for robbery came four days later. According to Catherine James, the Governor of the Stoke Heath YOI where he died, 'he did not steal anything himself. He was part of a group which went out from the home. At worst, he acted as a lookout.' Yvonne Scholes says: 'Joe told me he pleaded guilty because he couldn't take any more. At that stage, he was so ill in his head, he just wanted it to be over.'

Two weeks before his court appearance, alone in his children's home bedroom, he methodically slashed his own face 30 times with a knife. The deepest wound, across the bridge of his nose, went down to the bone. The room was covered in blood and had to be repainted. 'I still don't know how they could lock up a boy who had all these things happen to him,' says Yvonne. In any event, the judge decided Joseph's circumstances were not 'exceptional' enough.

In one sense, they weren't. A report last year on young prisoners by the Chief Inspector of Prisons, Anne Owers, found that while 'it was to be expected' that youths in custody might be among the most disadvantaged in the country, 'the extent of the deficits revealed during the course of the inspections alarmed even the inspectors familiar with the needs of this group.' Almost half had been in care, for example; 73 per cent described their educational attainment as 'nil'. In 1998, Wasted Lives , a study by the penal reform group Nacro, revealed young prisoners were very likely to have suffered deprivation of all kinds, physical or sexual abuse, and mental illness.

It was an awareness of such factors which drove the debate that followed the death of Philip Knight, and ensured it had such prominence. The virtual silence at that of Joseph Scholes is just another indicator of the very different penal climate. Or as Yvonne Scholes says: 'Joe wasn't a wild, young, persistent offender, he was a sick young boy who needed easing back into society. The sentence was a knee-jerk reaction to politicians and the media, who just lump all children who commit offences together. As far as they're concerned, they're all the same.'

As far as there is an intellectual element in this new, vengeful climate, it is to be found in the work of right-wing American writers such as James Q. Wilson, the architect of 'zero tolerance' policing, who wrote in the 1990s that young offenders had come to display 'the blank, unremorseful face of a feral, pre-social being'.

As my colleague Mary Riddell recently observed, the term 'feral', with its implication that youthful criminals can be regarded as less than human, is now the favoured buzzword of British commentators and tabloid headline writers. In 1996, President Reagan's former drugs czar, William J. Bennett, went still further than Wilson, warning that cities faced a race of 'superpredator' teenagers, against whom only the most punitive measures would suffice.

No doubt inadvertently, Lord Woolf echoed him in his mobile phones ruling, when he warned: 'This is a very serious social problem, and the only way the message is going to get home ultimately is a few sentences of exceptional severity.'

In the past three years, the Prison Service has poured resources into improving regimes for juveniles, especially in education, just as it has for adult prisoners. Yet it is an unequal struggle in which the pressure is constantly increasing, stoked by Government policy and the judges' increasing severity. There are almost 3,000 juveniles aged 15-18 in Prison Service institutions this weekend, about twice as many as there were in 1990 when Philip Knight died.

The juvenile prison population has risen rather more quickly than the adult one, which has increased from approximately 40,000 to 68,000 in the last decade. Blunkett's proposals for 'dealing' with persistent young offenders will see a further 600 move to youth jails from local authority secure units. From the Government's point of view, the advantage is not merely political, but financial. The Prison Service gets about �50,000 a year for a juvenile place, against �150,000 for the local authority units, with their much higher ratio of staff to inmates.

'There's no doubt there are countless people sent to custody who could be dealt with by community penalties,' says Martin Narey, the Prison Service Director-General. Many juveniles were being sentenced to YOIs for just a few months: long enough to stigmatise them and disrupt their lives, but 'time enough to do nothing in terms of social exclusion, drugs or education.'As for Scholes, says Narey, 'we did everything we could with a child who should not have been there'. Or as Yvonne Scholes puts it: 'How could they have locked up my ill, abused boy?'