Numerous miscarriages of justice have come to light in the last 15 years, but have changes to the law made fresh tragedies impossible or is there a need for a more radical and fundamental reform of the criminal justice system?
Rumblings of discontent with the British criminal justice system began to grow in the 1980s. Campaigns started to spring up around individual cases. The phrase "miscarriage of justice" was crystallised around two big cases - the Birmingham Six and the Guildford Four. Both stemmed from IRA outrages against civilian targets at the height of the bombing campaign.
Police appeared to have quickly rounded up the suspects and brought them to justice. In reality the wrong men had been convicted. It was only due to the determination and investigative skills of a TV documentary team and MP Chris Mullin, himself a former journalist, that the injustice suffered by the Birmingham Six came to light.
When they were released by the Court of Appeal in 1989 it seemed there was hope for dozens of prisoners who had been pleading their innocence in vain for years. Other campaigns sprung up and gradually, over the next 11 years, many of these succeeded - including the Guildford Four, Judith Ward, the Darvell brothers, the Cardiff Three, Danny McNamee, the M25 Three and the Bridgewater Four.
Even cases from beyond the grave, such as Derek Bentley and Hussein Mattan, have been revisited and names cleared. But there are still many people in prison proclaiming their innocence.
1989: The Guildford Four are released by the Court of Appeal. The detectives at the centre of the case are later cleared of fabricating evidence.|
1991: The Birmingham Six are freed. Prosecutions against officers accused of tampering with evidence are halted because of "adverse publicity".
1997: The Bridgwater Four - minus Patrick Molloy, who died in jail - are released after 17 years in prison.
2000: The M25 Three are freed by three Court of Appeal judges who say there had been a "conspiracy" to give perjured evidence.
A miscarriage of justice can result from non-disclosure of evidence by police or prosecution, fabrication of evidence, poor identification, overestimation of the evidential value of expert testimony, unreliable confessions due to police pressure or psychological instability and misdirection by a judge during trial.
Since 1984 two pieces of legislation have been introduced in an attempt to prevent further miscarriages. The Police And Criminal Evidence Act (PACE) gave detectives rigid rules on how long they could question suspects for and insisted interviews be taped to ensure there was no mistreatment or undue intimidation.
The Criminal Procedure and Investigations Act was also introduced in an attempt to make sure police or the Crown Prosecution Service (CPS) disclose to the defence everything which could be relevant to their case. However a recent review of disclosure undertaken by the Crown Prosecution Service Inspectorate found the CPIA did not have the "confidence of criminal practitioners".
Adversarial system under attack
Paddy Hill, one of the Birmingham Six, is sceptical such legislation is enough. Mr Hill, who has set up his own pressure group Miscarriages Of Justice Organisation (MOJO), told BBC News Online: "Justice is something that is not on this government's curriculum."
He said the criminal justice system needed a radical overhaul to make it "more open and accountable". Mr Hill would like to see:
The adversarial system replaced with a continental-style inquisitorial system, where the driving motive behind any police investigation is the search for the truth.
Juries forced to give their verdicts in writing, to amplify on their reasons and guard against the danger of "perverse" verdicts.
Judges and other judicial officials being elected, rather than chosen by "the establishment".
Changes in the law to ensure police officers who break the law are convicted and sent to prison.
Kevin Christian, whose brother Derek is serving a life sentence for a murder he denies committing, is a member of the pressure group Innocent. He told BBC News Online:
"The biggest problem seems to be the Court of Appeal and its lack of willingness to recognise and correct errors. The Guildford Four is a prime example. Even after the Balcombe Street Gang had admitted they were responsible for the Woolwich bomb, the Court of Appeal would not even entertain the possibility that the Guildford Four were innocent.
"The adversarial system means that the criminal justice system can easily turn into an upmarket local dramatic society with the two main protagonists being the prosecuting and defence counsels, the difference being that the defence counsel may not have had time to learn his lines before the curtain goes up."
Mr Christian favours the French system of investigating magistrates or the Staatsanwalte in Germany, in which the prosecuting lawyers are involved from the outset.
"A mixture of circumstantial evidence and tenuous or contentious forensic evidence can be very tempting to a jury. Many miscarriages result, ironically, from weak prosecution cases.
Where there is very little in the way of a prosecution case to dismantle, it is very difficult to mount a cogent defence case," he said.
Investigating alleged miscarriages
The Criminal Cases Review Commission was set up by the last government in an attempt to investigate alleged miscarriages of justice properly. It is an independent body responsible for investigating alleged miscarriages in England, Wales and Northern Ireland.
The commission has 14 members including chairman Sir Frederick Crawford, barrister Jill Gort, former chief constable Baden Gitt and journalist David Jessel, former presenter of Trial and Error and Rough Justice. Critics say it is under-funded, understaffed and not sufficiently independent. It currently has a backlog of 1,200 cases (about a third of all applications to date).
Chris Mullin MP, a former journalist for TV's World In Action, said: "Miscarriages of justice can occur under any system and I have no doubt they will occur in the future."
But Mr Mullin, nowadays a junior minister, told BBC News Online: "We should never be complacent. The system has improved considerably since the big miscarriages of the mid-1970s. PACE, which came in in 1983, had regulated interviews and improved the treatment of suspects and just about all interrogations are now recorded. But the most important change is that people who believe they are the victims of miscarriages of justice have somewhere to go: the CCRC."
He admitted the CCRC had a backlog and "could do with speeding up its handling of cases" but said it had a good track record. Mr Mullin said: "73% of cases which have been referred back to the Court of Appeal by the CCRC have resulted in quashed convictions."
Mr Mullin admitted the adversarial system had flaws and said: "There is a strong case for a system which finds the truth, rather than a contest between skilled adversaries. But you should realise that the continental inquisitorial system had also led to miscarriages of justice."
Police role 'exaggerated'
The Chief Constable of Kent, Sir David Phillips, is the Association of Chief Police Officers' spokesman on criminal justice and he admitted the system is not perfect.
"It's not safe. Far too many guilty people are acquitted to the danger of the public. We are too often strangled by a system of rules and interpretation, which prevents us getting to the truth," he said.
"While trials are contests, there is a high level of acquittals, which must mean either the police or the courts are getting it wrong. Very often the whole case is not heard. Juries are not able to put the whole picture together."
Sir David does not believe the adversarial system needs replacing but he would like to see changes. He said: "The defence should have to disclose their evidence so the court can take control of it. There is no reason why the defence should be able to keep evidence secret so it can be used in an ambush."
He believes there should be less of an emphasis on advocates' skills and more on the evidence. "Let the jury see the evidence. I am in favour of them seeing tapes of defendants being interviewed so they can make up their own minds," he said.
As for the police's role in miscarriages of justice, Sir David believes it has been exaggerated. "In the CCRC's annual report they said that where things had gone wrong it was rarely the police's fault. It was usually the defence or the prosecution."
When it comes to police officers who fabricate evidence to secure a conviction, he said ACPO was keener than anyone to see them prosecuted and convicted. "If people are going to tell lies about how they obtained evidence, you are going to have difficulties. Most cases of police corruption are discovered by the police and corrupt officers are one of our highest priorities to root out and prosecute," said Sir David.