The Police Complaints Authority said it agreed with the decision of Jack Ord, Deputy Chief Constable of Cleveland, that the officers involved in the arrest of Oliver Pryce in Middlesbrough in 1990 should not be disciplined.
The legal lobby group Inquest, which has been acting on behalf of Mr Pryce's family, said last night that a 'number of avenues' in the case were still being explored. It is believed that the family is considering the question of a private prosecution; a civil action is already being pursued.
Mr Pryce, 30, from Wolverhampton, a former British karate international who suffered from psychiatric problems, was arrested after jumping in front of an ambulance. He died from asphyxiation in the back of a police van.
An inquest jury last year returned a verdict that he had been unlawfully killed after hearing how the six officers bundled him into the van and one of them held him in a headlock.
An investigation supervised by the Police Complaints Authority led to an initial decision by the Crown Prosecution Service that the officers would not be prosecuted. The case was considered again after the inquest and the CPS took counsel's advice. It re-affirmed its position last month.
A spokesman for the Police Complaints Authority (PCA) said last night that it had agreed that insufficient evidence existed to prove 'beyond reasonable doubt' that the disciplinary offence of abuse of authority had been committed by police officers.
Police discipline procedures dictate that proceedings have to be brought according to the criminal standard of proof. In cases where the allegations are straightforward and the CPS has not pressed charges, it is difficult to argue that disciplinary offences have occurred. The authority said that at the time of the arrest of Mr Pryce, 'a significant majority of independent witnesses found no cause for complaint in the officers' behaviour'.
The statement added: 'Careful consideration was given to the treatment of Mr Pryce in the back of the van and especially the method of restraint used to contain him during the journey. The officers say that he was struggling violently as he was placed in the van and they feared he would start struggling again during the short journey to the police station. The authority was also unable to find any evidence to support the allegation that the police officers subjected Mr Pryce to racial abuse.
Deborah Coles, of Inquest, said yesterday that Mr Pryce's family was concerned at the inconsistencies between the position of the CPS and the PCA when compared to the decision of the inquest jury, which had considered the matter according to the criminal standard of proof and on the basis of the same evidence.
Yesterday's decision is likely to increase concern at the apparent inability of the system of investigating complaints against the police to bring proceedings. Lawyers have claimed that police have never been prosecuted in any cases where there have been allegations over the death of black people after their arrest.
The use by police of the headlock method of restraint has also caused concern in a number of cases, including that of Clinton McCurbin, who died while being arrested for shoplifting in Wolverhampton in 1987.