A Courtenay woman who fatally stabbed her partner in the chest while drunk on mouthwash was acting in self-defence, a B.C. Supreme Court judge has ruled.

In a decision posted Friday, Justice Lauri Fenlon acquitted Laura Lee Pierre of manslaughter in the killing of Allan Whitequill on Dec. 28, 2009, forgiving a number of gaps in her testimony that she chalked up to heavy intoxication.

Pierre and Whitequill lived together in a trailer where they spent the night in question drinking "significant quantities of Listerine" together, Fenlon wrote.

The defendant admitted to the court that she blacked out for portions of the evening, but remembered holding a knife in front of Whitequill as he sat on the bed holding blades of his own – a serrated bread knife in one hand and a straight-edged knife in the other.

"Her next memory is of the knife in Mr. Whitequill's chest and pulling it out," Fenlon wrote.

Fenlon ruled there was adequate evidence that a struggle had preceded the stabbing; Pierre had three cuts to her cheek, her necklace was broken and each of the three blades was found covered in blood.

Beads from Pierre's necklace were found on the bed, the floor and in Whitequill's navel, apparently having fallen into his shirt.

The judge gave Pierre credit for being candid and forthright on the witnesses stand, not altering her initial version of the events and demonstrating a "dogged adherence to relating only what she could recall."

Fenlon gave extra praise to the accused for even refusing to fill in gaps that would have helped her establish her claim of self-defence.

Pierre, who is 4-11 tall and weighs 99 lbs., was choked and had one of her front teeth knocked out by Whitequill in previous incidents, and Fenlon found she had reason to believe he could kill or seriously harm her the night he died.

"She also knew he had gone to jail for manslaughter for strangling a woman using a lamp cord," Fenlon wrote. "And, of course, Mr. Whitequill was holding two knives in his hands."

The judge found that there was insufficient room in the trailer to flee from a confrontation. After the stabbing, Pierre took immediate steps to save Whitequill's life, calling an ambulance and trying to stop the blood flowing from his body.

Fenlon found the defendant not guilty, ruling that she "did not intend to kill Mr. Whitequill or even to seriously injure him."

"I am left with far more than a reasonable doubt that the actions of Ms. Pierre constituted self-defence," she wrote.