Worboys was sentenced to an indefinite prison term with a minimum tariff of eight years after he was convicted of 12 sex attacks in 2009.
But speaking to MPs, Mr Gauke said he will not seek to block others from taking legal action against the move. He is believed to have sexually assaulted over 100 women in total, police say.
Similarly, on procedure it would be necessary to identify a failing to follow that process by the Parole Board that would have had a material impact on the decision'.
Gauke said he fully supports victims' rights to take their own advice and challenge the board's decision. "Vital that victims and public get to see Parole Board reasons because this decision is still deeply troubling and hard to fathom".
"The two women bringing the claim are doing so as they are convinced that Worboys remains a danger to women and that everything should be done to stop his imminent release. I will do all I can to ensure this happens".
Khan added: "Yesterday I informed the chairman of the Parole Board for England and Wales that I have instructed leading counsel on a possible judicial review of their decision to release John Worboys".
David Gauke, the new Justice Secretary, commissioned advice on the highly unusual step of seeking a judicial review himself last weekend.
"Whatever ones personal feelings about a case, ministers should not choose to bring legal challenge that has no reasonable prospects of success", he said.More news: Joel McHale Unveils New Topical Weekly Show On Netflix
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In a statement to the House of Commons, Mr Gauke said he could not give details of the legal advice receive but described the bar for a judicial review to succeed as "very high". "Having taken and considered expert legal advice, I have decided that it would not be appropriate for me as Secretary of State to proceed with such a case".
He confirmed that Worboys would not be freed until his license conditions have been finalised and that further meetings concerning his release are to take place next week. In this exceptional case, there is an over-riding public interest in understanding the basis for a decision which has caused such widespread concern amongst he very many victims and public at large.
The decision to release Worboys after nine years in prison has been criticised by numerous victims.
For many women, the UK's criminal justice system is now on trial.
And he announced a wide-ranging review into how the Parole Board works following complaints that victims were kept out of the loop.
"We can confirm that in the absence of any unexpected and compelling response from the Parole Board to our pre action correspondence, we intend to launch judicial review proceedings against the Parole Board next week".
Mr Gauke said there would be a wider review of how the Parole Board deals with victims that is expected to be completed before Easter.