Michael Howard's decision to make examples of the two 10 year-old boys - punishing them "in a blaze of publicity" as if they were adults - "flew in the face of common sense and the penal code of every civilised society", said Edward Fitzgerald QC.
Mr Howard should have put the cut-out coupons from the Sun, in which readers urged whole life sentences to be imposed, in the bin, said Mr Fitzgerald.
Instead, he should have called for social inquiry, psychiatric and other relevant reports. Not only did he ignore a requirement of both domestic and international law to consider the boys' backgrounds, he also ignored all mitigation on their behalf, said Mr Fitzgerald.
"No other country would have a situation such as this where a child as young as 10 can have a punitive sentence imposed by a politician," he said. The boys should be entitled to a regular review of their detention, he argued.
After recent clashes between Mr Howard and top judges over crime and punishment, the QC argued that sentencing was a matter for the judiciary - not the executive.
Mr Fitzgerald was launching a judicial review on behalf of Jon Venables and Robert Thompson of the Home Secretary's decision. The two boys were just ten-and-a-half, when three years ago they abducted two-year-old Jamie from a shopping precinct and killed him on an isolated railway line in Walton, Liverpool.
They were sentenced "to be detained at Her Majesty's pleasure" - the indeterminate and compulsory sentence for juvenile killers.
But their trial judge, Mr Justice Morland, recommended that they should serve a minimum eight-year "tariff" - the proportion of their sentence which reflects punishment and deterrence, before they can be considered for parole.
Lord Chief Justice Taylor, the most senior judge, recommended a 10-year tariff, but the Home Secretary, who makes the final decision, ruled that it should be 15 years.
Mr Fitzgerald said there was no challenge to the correctness of the convictions for what was "a horrifying crime" and both accepted responsibility for the tragic death of their victim. Nor was there any challenge to the need to detain the children for as long as was necessary to protect the public - however long that proved to be.
He told Lord Justice Pill and Mr Justice Newman that what was at issue was that Mr Howard's tariff decision unlawfully centred on "retribution and deterrence".
Mr Fitzgerald argued they had no place for children as young as 10, who were only just past the age of criminality - an age far lower that most other countries.
It ignored the fact that the children would mature and change and ignored statistics which showed that children rarely killed.
He knew of no other cases this century where a child killer had been as young as Venables and Thompson and one as young as 14 emerged only about once every five years.
"It's quite clear that this sort of crime is committed because of some aberration or problem in the young child."
"Who are you deterring?" asked Mr Fitzgerald. "Other children of 10?"
He maintained Mr Howard had no right to consider petitions, some gathered by Jamie Bulger's own family, calling for harsh minimum sentences. Of 22,630 letters received by the minister, 21,281 were Sun coupons urging the imposition of whole life sentences.
He said they were not expert evidence but merely representations from one section of the community.
"What are the consequences of that. Should legal aid be made available for detainees to conduct their own opinion polls? Any judge would throw them in the bin," he said.
Mr Howard is contesting the case, which continues today.Reuse content