An Ottawa recreation league hockey player convicted of aggravated assault for an on-ice collision will get a new trial after the Ontario Court of Appeal found the trial judge seemed to "impose her personal knowledge of hockey on the facts of the case." 

The panel of three judges found that Justice Diane Lahaie used "speculative reasoning" about hockey strategy to come to her guilty verdict in December 2013.

"From the sports pages to social media, it is abundantly clear that reasonable Canadians often disagree about what constitutes a rational hockey strategy in a given situation. Nor is there any source of indisputable accuracy by which to settle these disagreements," the court of appeal said in a decision released Monday.

The Crown had argued that Gordon MacIsaac blindsided Drew Casterton with a deliberate hit in the final 47 seconds of a game his team was losing in March 2012, leaving his opponent unconscious on the ice with cuts to his face and two broken teeth.

The defence had argued that MacIsaac was involved in an unavoidable face-to-face collision in a league in which bodychecking is banned but incidental contact is common.

During the trial, 11 witnesses testified, including MacIsaac, Casterton, other players from both teams and one of the game's referees. Lahaie noted in her decision that aside from the referee, there was bias depending on which team the witness played. 

Still, Lahaie accepted Casterton's testimony and rejected the testimony of defence witnesses based on how "illogical" she found their position or speed at that point in the game, the court of appeal found.

"The trial judge engaged in impermissible speculative reasoning in rejecting the evidence of the defence witnesses. This impaired the appellant's right to a fair trial," the decision said. 

On mobile? Tap here to read the full Ontario Court of Appeal decision.