When two or more service members are charged together and tried in a single court-martial, the proceeding is a joint or common trial. One accused may believe that being tried alongside a codefendant will unfairly taint the fact finder’s view of their own case. The remedy is a motion for severance, which asks the military judge to separate the accused so each is tried alone. The procedural standards for granting that relief are demanding, and they reflect a strong institutional preference for trying related matters together. Understanding which rule applies, what an accused must show, and how a denial is reviewed clarifies why severance is treated as an exceptional remedy.
The rules that govern joinder and severance
The Rules for Courts-Martial address joinder and severance in several related provisions. Rule for Courts-Martial 307 governs how charges and accused are referred and joined. Severance of accused is addressed under Rule for Courts-Martial 906(b)(9), while the closely related question of severing offenses charged against a single accused is addressed under Rule for Courts-Martial 906(b)(10). These provisions operate together, but the standards and the prejudice analysis are similar enough that the case law developed for severance of charges heavily informs how military judges evaluate severance of co-accused.
The manifest injustice standard
The governing threshold is strict. The rules permit severance only to prevent manifest injustice. This is a more restrictive standard than the analogous federal civilian rule, which allows severance on a broader showing of prejudice. The military standard reflects an institutional belief that court-martial members, who are selected for maturity, rank, and training, are better able than civilian jurors to compartmentalize evidence and to follow instructions limiting how they may use particular evidence. Because of that confidence in the fact finder, the moving accused must show something approaching a genuine inability to receive a fair trial, not merely some disadvantage from a joint setting.
The factors a military judge weighs
Military courts apply a three-factor analysis drawn from the severance case law to decide whether a denial would work a manifest injustice. The factors, articulated in cases such as United States v. Curtis and applied by the Court of Appeals for the Armed Forces, are whether the evidence of one matter would be admissible in a separate trial of the other, whether the military judge can give and did give an adequate limiting instruction, and whether the findings reflect an impermissible crossover, …