The two brothers found guilty of the manslaughter of schoolboy Damilola Taylor have lost their bids to have their sentences quashed.
Damilola Taylor bled to death in Peckham in 2000
The Court of Appeal heard applications on behalf of Danny Preddie, 18 and his brother Ricky, 19, both from Peckham, south London.
Both were convicted in 2006 after a protracted inquiry.
They were sentenced to eight years in youth custody for Damilola's killing in November 2000.
The court had also rejected an appeal by Danny Preddie to have his manslaughter conviction quashed.
Ruling on the sentences, Lord Justice Latham rejected argument that they were too long and said the courts had to send out the message that "violence of this sort will be punished severely and that will be the case even where the offenders are young".
Damilola, 10, bled to death after being cut with a broken bottle in a Peckham housing estate.
The long-standing inquiry into his death has led to three trials and cost £16m.
The Preddie brothers were 12 and 13 at the time of the killing
Earlier, Court of Appeal judges also threw out an application by Danny Preddie to be allowed to challenge his "unsafe" conviction.
Lord Justice Latham, giving the ruling of the court, said: "We ultimately conclude that the jury was entitled to be satisfied by the forensic evidence and such other evidence that they considered to be established to convict this young man."
The court had heard from Orlando Pownall QC, for Danny Preddie, who said the conviction was "unsafe" and that it was "unfair" to try him in 2006.
He said it had been too long after the crime for Danny Preddie to get a fair trial.
The Preddie brothers, 12 and 13 at the time, were arrested a few days after Damilola was killed but were released without charge.
They and a third defendant, Hassan Jihad, 20, went on trial in early 2006 for murder after new forensic evidence was found.
Mr Jihad was cleared of all charges.
But the Preddies went on trial at the Old Bailey for manslaughter, which they both denied, in June 2006.
They were convicted by a jury in August last year.