Virginia Hernando, 62, was acquitted by Justice Glenn Joyal, who said the Sept. 6, 2006 attack on her by her husband Alejandro was "inescapable," the Winnipeg Sun reported.
Court heard the husband had a history of "drunken violence and abuse" that led the woman to keep a knife beside the bed, of which her husband was aware.
The night of the stabbing, the couple was arguing about sending money to family in their native Philippines when the husband punched his wife and then grabbed onto her hair in a struggle.
Prosecutors said the wife's decision to keep a weapon "for a purpose dangerous to the public" directly led to her husband's death, but the judge disagreed in a 45-page ruling.
Joyal made his opinion on spousal abuse clear.
"I am in no way intending to endorse, sanction or otherwise justify a general practice of possessing a weapon for the purpose of deterring an abusive spouse, no matter how violent," he said.