Black cab rapist John Worboys could challenge the judgment blocking his release, Justice Secretary David Gauke has told MPs.
The admission came as Mr Gauke apologised in the Commons to the victims of Worboys, saying that the case "should have been much more effectively dealt with".
He told MPs that there "should have been much greater probing", adding: "I deeply regret that that did not happen. I'm sorry that that happened."
Former Tory minister Justine Greening later asked Mr Gauke to confirm whether the judgment itself could be challenged by Worboys, after three senior judges ruled that the Parole Board must make a "fresh determination" over whether he should be released.
He replied: "Yes, it is possible for this decision to be appealed."
Tory backbencher Zac Goldsmith later praised victims for campaigning for a judicial review and exposing the "profound errors" in the case.
He said: "The reality is that these victims have managed to blow open the system using a very big, popular campaign and they've given us a rare glimpse into something which I think many people across this House would find utterly terrifying the profound errors that have been uncovered by Leveson in the inquiry that he's just concluded."
Mr Goldsmith asked whether the Ministry of Justice review into the transparency of Parole Board decisions would be concluded before the next hearing of the Worboys case.
Mr Gauke said he would be "astonished" if the hearing went ahead before new transparency rules were in place.
Former Labour minister Yvette Cooper warned the Government benches that the Ministry of Justice had "serious questions" to answer.
She added: "It's not a good look simply to say this is about responsibility of the Parole Board if we're to get to the reforms that we actually need."
Earlier, the outgoing chairman of the Parole Board said there were "very troubling questions" about the body's independence after he was forced to quit over the Worboys case.
Professor Nick Hardwick was told his position was "untenable" after two victims won a High Court challenge against Worboys' release from prison.
He was not personally involved in the move to approve freeing Worboys but said he would not "pass the buck to those who work under me".
In a letter to Mr Gauke, he said: "I believe this matter raises very troubling questions about how the board's independence can be safeguarded."