The Government's chief law officer has decided not to challenge the sentences handed down to two brothers who sadistically tortured two young boys.
Last month the attackers, now aged 11 and 12, were sentenced to indefinite detention with a minimum term of five years for the brutal assault in Edlington, near Doncaster, South Yorkshire.
The Attorney General, Baroness Scotland, was urged to refer the sentences to the Court of Appeal.
But in a statement she said: "The judge was clearly correct to impose indeterminate sentences of detention and I agree with his analysis and with the minimum terms he set."
There was public outcry over the sentences, with commentators and children's charities suggesting it was wrong that the boys could be released before their 16th birthdays.
Lady Scotland called in the case papers, but today rejected the suggestion that the jail terms were unduly lenient.
In a statement she accepted the case was "truly shocking", but she said five years was the "very least" the boys would serve.
They will only be released when the risk they pose to the public is seen as "acceptable", she said.
"If I believe the Court of Appeal should examine a sentence I won't hesitate to ask," she said.
"In this case the judge approached the sentencing exercise with care and, after looking at all the factors involved, I do not consider the terms to be unduly lenient.
"I do want to emphasise an important point made by the judge, which is that five years is the very least these boys will serve.
"Both of these sentences will prevent the offenders' release from custody unless and until the Parole Board decides that the risk that they pose to the public is acceptable. Release is by no means automatic."
Sentencing the pair at Sheffield Crown Court, Mr Justice Keith described the crimes as "truly exceptional".
They were carried out "for no reason other than that you got a real kick out of hurting and humiliating them", he said.
The victims, then aged nine and 11, were lured to secluded woodland in April last year and subjected to 90 minutes of violence and sexual humiliation.
They were strangled, hit with bricks, made to eat nettles, stripped and forced to sexually abuse each other.
The older boy was seriously injured when part of a sink was dropped on his head.
Following sentencing, Doncaster Council apologised to the victims and their families for its failings in the case.
Claude Knights from charity Kidscape, which called for longer sentences, said she hoped the boys would not be released until they no longer posed a threat.
She said: "This was an appalling case which highlighted many issues, not least the failure of multi-agency working in Doncaster which missed 31 separate opportunities to take measures that would have prevented the horrific attacks.
"It is to be hoped that committed care professionals will now be working very effectively to rehabilitate these boys, and that they will not be released until it can be shown beyond reasonable doubt that it is safe to do so.
"In that way, the true value of indeterminate sentences will be demonstrated to the benefit of both victims and perpetrators."