Metropolitan Police (Met) officers assaulted a 16-year-old boy with severe autism by forcing him into handcuffs and leg restraints during a school trip, the High Court has ruled.
The judge said the boy, now 19, also had his human rights breached.
The boy, who also has epilepsy, was subjected to disability discrimination and false imprisonment, it was ruled.
He was awarded £28,250 in damages following the incident at a swimming pool in Acton, west London, in 2008.
'Refusing to apologise'
The force was refused permission to appeal, although counsel for the Met Commissioner said the application would be pursued directly with the Court of Appeal.
Outside court, the teenager's solicitor Tony Murphy said: "The commissioner, Bernard Hogan-Howe, is still refusing to apologise and has instead sought permission to appeal this judgement.
"He has used public money to defend the indefensible."
The boy, known only as ZH, was physically removed from the swimming pool and forcibly restrained after he jumped into the pool fully clothed.
The judge, Sir Robert Nelson, said although the officers attending the incident were acting as they genuinely thought best, their responses were "over-hasty and ill-informed".
Matters escalated to the point where a "wholly inappropriate" restraint of ZH, who cannot communicate by speech, took place.
By failing to consult his carers, the police failed to understand the potentially serious consequences of applying force and restraint to ZH, who was said to have suffered moderate post-traumatic stress disorder.
The judge said that ZH was at the pool for a familiarisation with four other pupils when he became fixated with the water and broke away from the group.
When the police arrived, they perceived it as a "life-and-death situation" as ZH, who could not swim but had no fear of the water nor indeed any knowledge of its danger, could have drowned.
When ZH moved closer to the pool, two officers took hold of his jacket as he began to gather momentum, but he was much too big and strong and ended up in the water, which was chest-deep.
Police van cage
ZH was moved to the shallow end and lifted out by lifeguards, with two police officers taking hold of his arms before handcuffs and leg restraints were applied.
Soaking wet, agitated and distressed, he was placed alone in a cage in the rear of a police van until calmed by carers and allowed to leave with them.
The judge said lawyers for ZH had established his claim for trespass to the person, assault and battery and false imprisonment under the Disability Discrimination Act and the Human Rights Act,
He said: "The case highlights the need for there to be an awareness of the disability of autism within the public services.
"It is to be hoped that this sad case will help bring that about."
The court heard it was the first time police in London had been found to have subjected a member of the public to inhuman or degrading treatment, and to disability discrimination.
A spokesman for the Met said they were giving the findings of the hearing "full and careful consideration".
He added: "We will be seeking legal advice and take forward any learning as appropriate.
"We are making an application for leave to appeal today."