OTTAWA - Canada's courts long ago determined that no means no when it comes to sex.

Now, the Supreme Court is considering to what extent yes means yes.

Justices are deliberating about whether a person can consent in advance to sexual activity that will take place when they're unconscious.

The court heard arguments today in a 2007 case involving a woman who was voluntarily choked to unconsciousness by her common-law spouse.

The Crown said the concept of consent implies the ability to change one's mind, which is impossible if a person is unconscious.

But lawyers for the accused argued that consensual sexual activities which happen when one person is unconscious are not necessarily criminal.