OTTAWA—Canada’s military justice system will be on trial again Friday, when an appeal court weighs whether the handful of judges responsible for overseeing courts martial are truly independent. The Court Martial Appeal Court hearing revolves around then-defence chief Jonathan Vance’s decision last year to place responsibility for the disciplining of Canada’s four military judges with an officer under his own command. The move followed the unprecedented court martial of chief military judge Mario Dutil, who was accused of fraud and misconduct. The case collapsed last year owing to questions about whether he could receive a fair trial in the military system. Three of the other four military judges have since stayed several cases, saying Vance’s order impinged upon their independence and thus robbed service members accused of wrongdoing of their right to fair trials. The fate of those cases now hangs in the balance as three of the military appeal …