A friend of murdered teenager Stephen Lawrence cannot sue the police for negligence, Law Lords have ruled.
Duwayne Brooks had claimed police treated him like a criminal
Duwayne Brooks wanted to take the action over the way he was treated after the 1993 attack in Eltham, south-east London, which he witnessed.
He claimed that he was treated as a criminal and went on to suffer from severe post-traumatic stress disorder.
Five Law Lords unanimously agreed the negligence claim be struck out, but Mr Brooks could pursue other claims.
Mr Brooks called the ambulance when 18-year-old Mr Lawrence was stabbed in the "most notorious racist killing which our country has ever known", said Lord Bingham. No-one has been convicted of the killing.
In March 2002, Mr Brooks won the right to bring proceedings against the Metropolitan Police Commissioner for false imprisonment and negligence and named police officers for breaches of the Race Relations Act.
His solicitor, Jane Deighton, described that Court of Appeal decision as "ground-breaking". It was the first time that the rights of the victims and witnesses of crime against the police had been recognised in law.
Mr Brooks claimed police should have taken reasonable steps to assess whether he was a victim of crime and then to accord him reasonably appropriate protection, support, assistance and treatment if necessary.
They should also have done the same because he was a key witness to a serious crime of violence, Mr Brooks claimed.
Finally, he said, they should have afforded reasonable weight to his account of the killing and acted upon it accordingly.
However, Lord Bingham and four other Law Lords on Thursday unanimously agreed that there was no basis for imposing on the police any of the legal duties asserted by Mr Brooks.
Lord Bingham added that no matter how sensitively Mr Brooks had been treated by police nor how well the crime had been investigated, he would have been deeply traumatised by the experience.