The boy, from Portsmouth, had entered 22 guilty pleas in July for myriad offences including sexual assault, racially aggravated assault, theft, common assault and criminal damage, but a judge heard that his low IQ meant he could not properly understand the court process and so his guilty plea could not be accepted.
The judge said the case was the 'perfect storm' after the court made 15 various attempts to deal with the child.
Psychiatric and psychologists' reports said the boy had an IQ of 58, which meant he was in the bottom three per cent for his age. This, experts claimed, also left him unable to understand the implications of his acts.
On that basis, district judge Anthony Callaway allowed new, not guilty pleas to be entered for all the charges under common law powers.
Doctors recommended the boy – who is in foster care – should be given a hospital order under the Mental Health Act, but as he was not convicted, that could not be implemented.
David Tongs, from the youth offending team, told the hearing at Fareham Youth Court the child's behaviour had 'deteriorated beyond control' in recent weeks.
"Since his last appearance, his behaviour has become rather worrying," Mr Tongs said, "He's become abusive, he's been running away almost on a daily basis, and running away from school almost as soon as he's taken there."
"He's been breaching his curfew. On one occasion he was just standing outside and refusing to come in," he said, adding "We worry that he's out with other young people who are known to us as criminally active."
Mr Tongs told the court that the young boy had tried to stab a teacher with a pen and damaged several windows at his school in recent weeks.
"His behaviour over the last two to three weeks has been appalling. It's deteriorated beyond control," he said.
His foster carer told the hearing that his behaviour was now at a 'difficult level', adding "I don't know how to keep him safe."
District Judge Callaway said that the boy's crimes were serious, but he could only apply the law as it stood.
"Nobody listening to what has been outlined in this case could think otherwise than that this young man has been very difficult, not only to himself but also to members of the public," Judge Callaway said, "These crimes are serious and they represent not only serious damage to people's property, but to people themselves and their right to carry on with their lives as they wish. However, the court can only apply the law as it is - not as it would like it to be."
"The only option this court can make is for the matters before me to be absolutely discharged. That is not a course that particularly commends itself to me but it is the only course open to the court."
"I'm afraid as far as I understand it, I don't think there is any way home in the law as it presently stands. We can debate it as long as we like, saying how wrong it is," he concluded.
The Mail reports that the boy's defence lawyer, Lian Webster-Martin, said she did not 'seek to say that an absolute discharge is in the boy's best interest' but added 'we have looked at every possible avenue.'