Marc Dutroux is one of Belgium’s most reviled criminals, serving a life sentence for the abduction, rape and murder of several girls and young women in the 1990s.

Now Mr. Dutroux, a former electrician who has been held in solitary confinement for 23 years for crimes that gripped Belgium, has won a court victory that could eventually lead to his release on parole.

No matter that Mr. Dutroux abducted and raped six girls ages 8 to 17 in 1995 and 1996, his lawyer argues; or that he filmed the assaults; or that he killed four of them, burying two alive and leaving the others to die of starvation in an underground cell where he left them while serving a prison sentence for car theft.

The lawyer, Bruno Dayez, said in a phone interview on Tuesday that Mr. Dutroux’s punishment had been “sufficient” and that it was time for Belgium to “turn the page.” An earlier request for his conditional release, in 2013, was denied.