Jack Straw won the support of opposition parties today to rush through emergency laws to protect anonymity in court hearings.
In a Commons statement, the justice secretary said the bill, which is still being drafted, would be published next week and pushed through before MPs leave Westminster for the long summer break on July 22.
The move comes after a law lords ruling against anonymous evidence led to the collapse of a murder trial at the Old Bailey on Tuesday.
The prime minister, Gordon Brown, promised urgent action, amid fears that other high-profile cases would be damaged and appeals launched against previous convictions.
In a statement to MPs, Straw said a "significant" number of ongoing cases, including violent disorder, terrorism and murder, were potentially affected.
But he assured the Commons that the legislation would ensure already convicted criminals would not be able to appeal on the basis of the "technical deficiency".
The legislation will set out details of the process for allowing witnesses to remain anonymous and require that a judge "will have to be satisfied that the need for anonymity is satisfied, that a fair trial will be possible and that it is in the interests of justice".
Straw said: "Anonymous evidence is these days fundamental to the successful prosecution of a significant number of cases, some of which involve murder, blackmail, violent disorder and terrorism.
"Such cases would be jeopardised if we do not quickly fill the gap created by their lordships' judgment."
But he insisted he was not seeking to make use of anonymous evidence routine, and stressed his new law will be compatible with the European convention rules.
He added he will be looking at experience in New Zealand, where in effect a special prosecutor can give advice on the credibility of witnesses.
Opposition parties gave their tactic support for the move but the shadow justice secretary, Nick Herbert, warned that the history of such emergency legislation was "not a happy one".
Straw gave an undertaking that the new laws will be revisited when he publishes a long planned bill on witness protection.
Herbert said: "No one wants to see a situation where violent criminals evade the law... But the use of anonymous witnesses in criminal trials should always be a last resort not a first response."
He said the purpose of the legislation "should not simply be to allow the use of anonymous evidence, but to ensure above all that justice is done."
David Howarth, the Liberal Democrat justice spokesman, said it is fundamental that the rule of law has to be defended against intimidation and threats, and said he would co-operate in passing the emergency laws.
He, like Herbert, praised the judges for pressing for parliament to think more seriously about the use of anonymous evidence, and said some of the criticism of the judges in the media had been scurrilous since it msunderstood the role of the courts.
Lord Thomas, the Liberal Democrat justice spokesman in the Lords and a practising barrister, was more critical, saying the police in London were now using anonymous witnesses as a matter of routine.
It is likely the Liberal Democrats will take a more sceptical tone when the major piece of legislation comes before parliament following the Queens speech.