Later this week, the High Court is expected to hear a claim for judicial review brought by two women known as DSD and NBV. Both were sexually assaulted by John Worboys. The former London taxi driver is thought to have committed well over 100 rapes and sexual assaults in his black cab between 2002 and 2008. DSD was one of his first victims. NBV was around his 75th.

The two women brought successful claims for damages against the Metropolitan Police, arguing that Scotland Yard was required by the Human Rights Act to hold an effective investigation into allegations of inhuman or degrading treatment – and had failed to do so. It is nearly a year since the Supreme Court heard an appeal by the police and judgment is still awaited, suggesting deep disagreement among the justices.

DSD and NBV are now challenging a decision by the Parole Board that Worboys no longer needs to be detained for public protection. He has been in custody for almost 10 years, two years more than the minimum term of his indefinite sentence.

The first problem the claimants face is that they do not know why the board thought Worboys could safely be released on licence. We know the decision was taken – curiously, on 26 December – by a three-member panel chaired by one of the board’s most experienced women members. The panel, which included a psychologist, considered a 363-page dossier and heard evidence from four other psychologists as well as prison and probation staff responsible for Worboys. The justice secretary was represented by a probation officer – who would not have argued for or against release. Worboys himself was questioned in detail. The panel considered a written statement from one victim. 

We have not been told the panel’s reasons because rule 25 of the Parole Board Rules 2016 says that ‘information about proceedings under these rules and the names of persons concerned in the proceedings must not be made public’. Those rules were made by ministers little more than a year ago, though they reflect earlier practice. 

However, DSD and NBV argue that the Criminal Justice Act 2003 does not give ministers the power to make such wide-ranging publicity restrictions. Phillippa Kaufmann QC, for the two claimants, says in written submissions that ‘rule 25 is ultra vires section 239 of the 2003 act’. That’s because the Parole Board is, in effect, a court. Any exceptions to the principles of open justice must be strictly necessary or expressly authorised. Some names and details of a ruling might need to be kept private. But ‘a blanket ban on the giving of reasons and disclosure of evidence in Parole Board cases is a disproportionate means to achieve whatever legitimate interests may be pursued by secrecy in these cases’. 

The justice secretary disagrees. David Gauke is reviewing rule 25. In the meantime, he maintains, the open justice principle does not apply to Parole Board hearings.

Nick Hardwick, the Parole Board chair, rightly supports greater openness. But it is still a bold submission to argue that a longstanding non-publication rule is intrinsically unlawful. So the courts may uphold rule 25 and let Gauke design a new publication policy.

If they lose that point, the claimants have a fall-back position. Even though they do not know the full facts, they argue that the decision to release Worboys is irrational, and therefore unlawful, on the information currently known. 

Worboys was maintaining his innocence as recently as May 2015. So he would have had two-and-a-half years at most to address his offending behaviour and accept that he was guilty of the all the offences the police believe he committed. He would presumably have completed a sex offenders’ treatment programme in prison. But an impact evaluation published by the Ministry of Justice a year ago suggested that men who took the course were, if anything, slightly more likely to reoffend.

And Worboys is not likely to have matured much in prison. Now 60, he was in his mid-40s when he began to offend. He was not an addict, mentally unwell or even angry.

Only two years before the decision to release him, Worboys was apparently regarded as unsafe for transfer to open conditions – usually regarded as an essential precursor to release. Indeed, he is said to have served nine years at the Category A high-security Wakefield prison, suggesting that until recently he was seen as very dangerous.

But, as the justice secretary reminded parliament on 19 January, the bar for a successful judicial review challenge is set high. Having seen the panel’s findings, Gauke felt unable to argue that no reasonable person would have reached similar conclusions or that there had been significant procedural failings.

Would we all feel safer if Worboys remains behind bars? Certainly. But that’s not the question the High Court is being asked.