Adrian Walle had asked the high court to overturn his conviction in the killing of Jeffrey Shuckberg eight years ago.
Walle had been kicked out of a pub in the city's southwest when he shot and killed Jeffrey Shuckberg in January 2004.
Walle was convicted of second-degree murder and sentenced to life in prison with no chance of parole for 13 years.
In 2010, the Alberta Court of Appeal rejected Walle's argument that the trial judge failed to consider his mental state on the night of the shooting, including developmental delays and the fact he'd been drinking.
Today, the Supreme Court agreed with the appeal court, saying the trial judge took all the relevant evidence into consideration.