By a unanimous decision of its 18 members the commission has ruled that Mr Howard has no right to decide when juvenile criminals "detained at Her Majesty's pleasure" should be released from jail.
Lawyers representing Jon Venables and Robert Thompson, both aged 11, who were convicted of the 1993 murder of the Liverpool two-year-old, have already started a legal campaign to take advantage of the commission's decision.
An application has been lodged at the High Court for a judicial review of the fairness of the 15-year minimum sentence. Meanwhile the commission will announce this week that it has agreed to a request by the boys' legal advisers to list their cases for apossible hearing in Strasbourg.
Both the High Court and the commission will be asked to consider whether it was right to try the boys in an adult court.
News of the commission's ruling was greeted with fury by Mr Howard's supporters yesterday. Sir Ivan Lawrence, the Conservative chairman of the Commons Home Affairs Committee, said that Britain should consider withdrawing from the European Convention for Human Rights if it kept losing key cases.
"There is growing concern that the traditions of this nation on law and order are being eroded by people from other countries who do not understand our history and procedures," he said. "It is a bit rich for a commission with people on it from regimes which are not respectable to tell us what to do."
Many lawyers, who are critical of what they see as the Home Secretary's political interference in the judicial process, will be delighted by the decision.
John Wadham, the legal officer for Liberty, said: "It's high time politicians got out of the judicial process."
At present the British Home Secretary can raise the minimum sentence of a child killer who is detained at her Majesty's pleasure. He can also decide whether it is safe to release the criminal once this "tariff" period - the minimum prisoners must serve before they can be considered for release - is over.
In the Bulger case, the trial judge recommended the boys serve at least eight years for luring James Bulger from a shopping centre and killing him by a railway line.
The Lord Chief Justice raised the tariff to ten. The Home Secretary then increased it to 15 years after protests from Liverpool against this allegedly lenient sentence.
Tomorrow's commission ruling is based on the cases of two murderers, Prem Singh and Abed Hussain, who were 15 and 16 when they were convicted.
The commission has decided that the Home Secretary has no right under European law to say when it is safe to release criminals convicted as juveniles from a life sentence.
The commission's decision has to be ratified by the European Court, but it has never overturned a unanimous recommendation.Reuse content