The board reviewed the case of Steve Ewanchuk after it denied his statutory release one year ago.
It says the 66-year-old Edmonton man has since completed a sex offender program but remains a risk to reoffend.
Ewanchuk has a criminal record of sex assaults on young girls and teens that spans four decades.
He came to notoriety in 1999 in what was dubbed the "no means no" court battle that clarified Canada’s sex assault laws.
The Supreme Court convicted him of sexual assault for groping a 17-year-old during a job interview, even though she told him three times to stop.
Alberta's Court of Appeal had upheld Ewanchuk's acquittal, with one judge remarking that the teen "did not present herself in a bonnet and crinolines" and that Ewanchuk’s advances "were far less criminal than hormonal."
The Supreme Court said the judge's comments reinforced a stereotype that females invite sex assaults through their appearance. The high court then changed the country’s sex-assault law to put the onus on the initiator of sex to obtain consent.
In 2007, Ewanchuk was sentenced to 11 years for sexually assaulting an eight-year-old girl.
His sentence expires in February 2018. When he is released, he is to remain under a 10-year supervision order.
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