The appellant was convicted of second degree murder after killing the victim with a hammer and knife.
At trial, his sole defence was self-defence.
A key Crown witness, the appellant's former partner, gave testimony that differed from her initial police statements.
To explain the inconsistencies, the Crown called expert evidence on Battered Women's Syndrome and Post-traumatic Stress Disorder.
On appeal, the appellant argued the expert evidence constituted impermissible oath-helping and that the jury instructions on reasonable doubt were flawed.
The Court of Appeal found that while the expert evidence improperly crossed the line into oath-helping, the error occasioned no substantial wrong given the overwhelming circumstantial evidence against self-defence.
The conviction appeal was dismissed, but the sentence appeal was allowed, reducing the parole ineligibility period from 15 to 12 years.
