Paul Tatton has been charged with arson in 2010 after police alleged he had deliberately set the fire at the residence of his former girlfriend.
At his trial, the court heard that Tatton, in a highly intoxicated state, had placed a pan with oil on a stove, set the burner to high, and left the house to get a coffee.
When he returned approximately 20 minutes later, the house was on fire. He had argued at his trial that the fire was an accident.
The trial judge determined that arson required specific intent and acquitted him, and the Court of Appeal upheld the decision.
Arson doesn't require 'complex thought'
In its decision Thursday, the Supreme Court of Canada overturned the lower court decisions and ordered a new trial, saying arson does not require specific intent and that "self-induced intoxication short of automatism is not available as a defence."
"The mental element is the intentional or reckless performance of the illegal act," the court wrote in its ruling.
"No additional knowledge or purpose is needed. No complex thought or reasoning processes are required. It is difficult to see how intoxication short of automatism would prevent an accused from foreseeing the risk of causing damage to someone else's property by fire."
The court said the trial judge erred in considering how intoxicated Tatton was.
"A new trial is required because the trial judge's critical findings of fact were tainted by his belief that self‑induced intoxication was relevant to the issue of intent," they said.