Criminals convicted by anonymous evidence could launch appeals
Criminals could walk free from prison because of a "potentially disastrous" ruling by the Law Lords, a senior Metropolitan Police officer has said.
Defendants in criminal trials now have a legal right to know the identity of witnesses testifying against them.
John Yates told the Daily Telegraph convicted criminals could appeal and be freed if witnesses refused to reveal their identities in a retrial.
Ministers said the issue of protecting witness identities would be addressed.
Police in London believe up to 40 criminals could now launch appeals, the Telegraph reports.
Mr Yates, who is assistant commissioner of the Met, made his comments after Iain Davis' double murder conviction was quashed by the Law Lords.
He said: "A lot of good work being undone, and this will play out so badly in terms of those we are trying to reach out to in communities. It almost feels like we have broken our word.
"To see clearly guilty people walking free is just awful.
"Special measures are only used in the most extreme cases, which means these are our most dangerous criminals, people who have been jailed for up to 40 years. And they could be walking free."
Justice Secretary Jack Straw told BBC Radio 4's Today programme the issue of protecting witness identities would be addressed "very urgently".
"It is fundamental that defendants should be able literally to see and hear the evidence before them.
"But you have to balance that against what actually happens in real life these days where you've got very serious gun and drug crime and there is a such a high level of fear."
Davis was convicted of killing of two men in a shooting at a flat in Hackney, east London, on New Year's Day 2002.
At the trial in 2004, seven witnesses claimed to be in fear for their lives if it became known that they had given evidence against Davis.
In order to persuade them to give evidence against the accused, trial judge David Paget QC allowed witnesses anonymity.
Without the evidence of three of the witnesses, Davis would not have been convicted, said Lord Bingham, the head of the panel of judges who sit at the country's highest court, at the House of Lords.
But he ruled: "I feel bound to conclude that the protective measures imposed by the court in this case hampered the conduct of the defence in a manner and to an extent which was unlawful and rendered the trial unfair."
He, along with four other Law Lords, allowed Davis' appeal and sent the case back to the Court of Appeal, which was asked to quash the conviction.
It was also asked to decide whether to order a retrial if an application was made by the prosecution.