- Video report by ITV News Political Correspondent Paul Davies
A decision to release black cab rapist John Worboys has been overturned by the High Court after a challenge by two victims.
Three leading judges in London have ordered the Parole Board to carry out a "fresh determination" before a "differently constituted panel".
The 60-year-old, who police believe committed crimes against more than 100 women, will remain in prison pending the outcome.
Sir Brian Leveson, Mr Justice Jay and Mr Justice Garnham said the Parole Board should have undertaken "further inquiry into the circumstances of his offending".
The judges added that in the light of their findings, the "release decision will be quashed".
Speaking during Prime Minister's Questions, Theresa May praised the "brave" victims who brought the legal action.
Mrs May also said the High Court decision gives rise to "serious concerns" about Parole Board processes.
Mrs May continued: "One of the issues that they have raised is they have found that it is unlawful to have a blanket prohibition of disclosing Parole Board information.
"That is something the Justice Secretary had already been looking into and has made clear that he will be ensuring that is dealt with as soon as possible."
Victim: 'The whole system that has failed'
One of the women who brought the High Court challenge, who can only be identified as DSD, said she had been "let down at every step".
Speaking after the court ruling, she said: "It is the whole system that has failed. She added: "It is wrong that we have been put in this situation.
"As victims we should have been supported and not having to fight every step of the way in court."
But DSD said she has confidence the Parole Board will now make the right decision, despite getting it "wrong" last time.
Parole Board chair 'sorry for mistakes in this case'
The chairman of the Parole Board, Nick Hardwick, who was not involved in the decision of the panel to release Worboys, resigned ahead of the ruling.
In his resignation letter to Justice Secretary David Gauke, he wrote: "You told me that you thought my position was untenable."
"I am sorry for the mistakes that were made in this case but I have always made it clear that I will support the members and staff of the board in the very difficult individual decisions they make and I will accept accountability for the work of the board," he continued.
Justice Secretary: Hardwick resignation 'correct' decision
In a statement, David Gauke said: "I accept Professor Hardwick's resignation and believe this is the correct decision in light of the serious failings outlined in today's judgment."
He added: "I want to take this opportunity to reiterate my heartfelt sympathy for all they, and the other victims, have suffered as a result of Worboys' hideous crimes."
Government to overhaul Parole Board decision system
In a statement to the Commons, the Justice Secretary set out the Government's response in the wake of the "unprecedented" judgment.
Mr Gauke confirmed that he intends to create a mechanism to allow Parole Board decisions to be challenged.
Under the plans a judge-led panel of different Parole Board members would re-examine cases if they are queried.
A rule barring the board from publicly disclosing information about proceedings will be abolished and the organisation will be given permission to make summaries of decisions available to victims.
The overhaul will also see:
- New guidance issued so that all relevant evidence of past offending should be included in dossiers submitted to the Parole Board
- Procedures put in place to check every dossier sent to the Parole Board by HM Prison and Probation Service (HMPPS) contains every necessary piece of evidence, including sentencing remarks or other relevant material from previous trials or civil legal action.
- A boost to the role of the Justice Secretary's representative at Parole Board hearings
- Work carried out to review the make up of Parole Board panels to include greater judicial expertise for complex, high-profile cases.
- More specialist training developed for panel members.
Victims launched challenge after 'irrational' decision
Lawyers for two women, who cannot be named, argued that the Parole Board's decision to release Worboys was "irrational", and should be overturned.
They said something went "badly wrong" and the board should have taken into account "critical evidence" of the "wider allegations" against Worboys.
At the conclusion of the hearing on March 14, the judges continued a temporary bar preventing Worboys' release, originally granted in January, following the legal action.
Worboys: A serial sex attacker
Worboys was jailed in 2009 after being found guilty of 19 offences, including rape, sexual assault and drugging, committed against 12 victims.
He attacked some of his victims in his hackney carriage.
Police believe he committed crimes against more than women between 2002 and 2008.
Parole Board: Judgement will open up 'decision making'
In a statement, the Parole Board said it would not challenge the judges' ruling which could lead to major reform it has been calling for.
"As a result of the bravery and determination of the women who brought this challenge, the experience of victims will be better and there will be much simpler ways to challenge our decisions in the future.
"It was clear before the Worboys case arose that there was a compelling case for major reform of the parole system. This judgment will now open up the decision making of the board which we have been calling for.
Other reaction to the decision:
Law firm Slater and Gordon, who represented 11 of Worboys' victims, said its clients were "delighted and deeply relieved".
Kim Harrison, a specialist abuse lawyer with the firm, said: "Our clients, who have been terrified that he will track them down after his release, can now sleep easy in their beds safe in the knowledge that this serial sex offender will be kept in jail where he belongs."
A spokesman for the Sun newspaper, which brought a legal challenge regarding the secrecy surrounding the Parole Board's decision in the case, said it was a "victory for transparency".
"Today's ruling is a landmark judgment in favour of open justice and will allow the decisions of the Parole Board to be subject to the scrutiny they deserve," he added.
Shadow justice secretary Richard Burgon said: "The failures in this case go much wider than the rules governing the Parole Board.
"We need a thorough examination of the handling of this case, from the first reported attack to the police by a victim right through to the parole board hearings.
"Anything less an independent end-to-end review into the whole handling of the Worboys case will fail to re-establish public confidence in our justice system and will let victims down again."