TORONTO - The notion of "advance" sexual consent will be up for debate Monday as a women's group appears before the Supreme Court in an effort to protect assault victims.

"This case has the potential to significantly change sexual assault law, and in a way will be potentially dangerous for the real lives of women," said Joanna Birenbaum, legal director for The Women's Legal Education and Action Fund or LEAF.

The Toronto-based organization will appear before the Supreme Court in the case of R. versus J.A. to argue the court should not introduce the concept of "advance" consent to sexual relations into Canadian law.

"This will be turning the clock back 20 years and risks re-introduing implied consent into Canadian law when it has been so definitely rejected both by the legislature and the Supreme Court of Canada," said Birenbaum.

The case before the court involves a woman who reported she was sexually assaulted by her common-law spouse, identified in court documents only as J.A.

On the night in question, J.A. strangled the woman into unconsciousness for what she estimates was approximately three minutes. When the woman awoke, she found herself bound and being anally penetrated with a dildo.

The accused J.A. said the woman consented "in advance" to the strangulation and the anal penetration that would take place while she was unconscious.

"The accused is asking the court to essentially develop a new doctrine in law," said Birenbaum.

"LEAF is arguing that consent in advance ... is not recognized in law, would require legislative change to be recognized in law and should not be recognized in law."

The woman in this particular case first told police she did not consent to the sexual activity. That statement was later recanted. Her evidence at trial was described by the judge as a "typical cross-examination of a recanting complainant in a domestic matter."

The trial judge concluded that the complainant could not legally consent in advance to sexual activity while unconscious. On appeal however, court heard that where a person consented in advance to sexual activity expected to occur while unconscious and did not change their mind, the Crown could not prove lack of consent.

LEAF is now arguing that any recognition of "advance" consent in law would have significant and serious implications for the safety of women, particularly vulnerable women such as those who are intoxicated, have disabilities or are Aboriginal.

If "advance" consent were to be passed into law, it would become a pervasive defence in which an accused person could argue a complainant gave consent at an earlier time, said Birenbaum.

"I'm very concerned that it will allow sexual history evidence considerable weight," she said.

LEAF will argue that should the new concept be passed into law, the burden will shift to women to prove they never gave "advance" consent, rather than their intimate partners being responsible for ensuring consent at the time of the sexual activity.

"It makes a mockery of the current definition of consent," said Birenbaum.

"The legal understanding of consent is that it must be active, voluntary and revocable, and when we're talking about 'advance' consent sex when a person is unconscious or incapacitated, it's no longer revocable."

Blair Crew, a criminal law professor who is also with the University of Ottawa's community legal clinic, said there's no doubt the case could set a significant precedent.

"It reaches to women who are passed out after they are drunk, who are passed out after being administered a drug, women who are asleep," said Crew, who has been observing the progress of the case for some time.

Crew explained that even today the law implies that consent must be ongoing, but doesn't explicitly spell it out.

Regardless of which way the Supreme Court rules, Crew said the case should ultimately result in a clear understanding of whether "advance consent" is acceptable.

But, Crew warned, passing "advance" consent into law would make it very hard for someone to ascertain whether what they agreed to was actually what happened once they were unconscious.

"It might open the door to all kinds of conduct with usually the woman having very little ability to oppose it because she's not even alert to what's happening."