An Ontario judge has ruled that a federal law preventing the so-called "intoxication defence" in sexual assault cases is unconstitutional.

That means people accused of sexual assault in the province are once again allowed to use excessive intoxication as a defence against criminal charges.

The judge's decision comes in support of Cameron McCaw, a Toronto man due to stand trial for sexual assault next month.

Justice Nancy Spies says he wishes to argue that he had consumed so much alcohol on the night of the alleged incident, he was unaware of his actions.

Farrah Khan, manager of Ryerson University's Office of Sexual Violence, says the ruling sends a disturbing message to women who may now feel that perpetrators can drink with impunity.