The ruling reverses an earlier Ontario Court of Appeal decision that had ordered Yousanthan Youvarajah to face a second trial in the 2007 killing.
The Supreme Court overturned that decision by a 5-2 margin, which ends the prosecution of Youvarajah on this matter.
Youvarajah and a youth were charged in the death of a small-time drug dealer.
The youth implicated Youvarajah in a signed statement and was allowed to plead to a lesser charge.
At Youvarajah's trial, the youth changed his story and the trial judge ruled the signed statement was not reliable, leading to the acquittal.