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, meaning that evidence relevant only to one accused or charge improperly influenced the result on another.
Applied to co-accused, the inquiry asks whether evidence against one defendant would be admissible against the other if they were tried separately, whether a limiting instruction can fairly confine the members’ use of evidence to the accused to whom it pertains, and whether the verdicts show that the members kept the cases distinct rather than blending them. If the evidence is largely cross-admissible and a proper instruction can guide the members, the case for severance is weak. If evidence damaging to one accused would be inadmissible against the other and no instruction could realistically prevent spillover, the case for severance grows stronger.
Mutually antagonistic defenses and confrontation concerns
Two additional concerns frequently drive severance motions involving co-accused. The first is antagonistic defenses, where each accused seeks to exculpate themselves by inculpating the other, so that the trial becomes a contest between the defendants as much as between the Government and each accused. The second is a confrontation problem that can arise when a non-testifying codefendant’s statement implicates the other accused, raising issues under the Confrontation Clause and the rules of evidence. Military judges manage these problems with tools short of severance where possible, such as redacting statements, giving tailored limiting instructions, or, in appropriate cases, severing the accused so that each statement is used only in the trial where it is admissible. Severance becomes necessary when these lesser measures cannot cure the prejudice.
Standard of review and the consequences of error
A military judge’s ruling on a severance motion is reviewed for abuse of discretion. The appellate court does not substitute its own judgment for the trial judge’s; it asks whether the ruling was within the range of reasonable choices given the record. Even where a judge errs, reversal generally requires a showing that the error caused actual prejudice. In United States v. Giles, 59 M.J. 374 (2004), the Court of Appeals for the Armed Forces found that a military judge abused his discretion and caused actual prejudice by denying a severance, illustrating that while the standard is strict, it is not unattainable when the record shows the accused was genuinely deprived of a fair trial. That case underscores the analytical structure: the appellate court examined cross-admissibility, the adequacy of the instructions, and whether the findings reflected impermissible crossover.
How a severance motion is litigated
Because the standard is so demanding, a persuasive motion to sever co-accused does more than assert generalized prejudice. It identifies specific evidence that would be inadmissible against the moving accused in a separate trial, explains why a limiting instruction cannot cure the resulting spillover, and shows how the joint setting creates a real risk that the members will use evidence across defendants. Where antagonistic defenses or a codefendant’s incriminating statement is involved, the motion explains why redaction or instructions will not suffice. The defense should also preserve the issue for appeal by making a clear record, since the appellate court will review the same factors the trial judge considered.
Severance of co-accused in a court-martial is therefore available but exceptional. It is granted only to prevent manifest injustice, evaluated through the cross-admissibility, limiting-instruction, and crossover factors, and reviewed on appeal for abuse of discretion with a requirement of actual prejudice. Service members tried jointly who fear unfair spillover should raise these concerns early with qualified defense counsel, who can build the specific record the standard requires.
Disclaimer
This article is provided strictly for general educational and informational purposes. It is intended to explain how the Uniform Code of Military Justice (UCMJ), the Rules for Courts-Martial, the Military Rules of Evidence, and related military administrative processes work as a matter of public legal education. It does not constitute legal advice, a legal opinion, or a recommendation about any particular case, and it is not a substitute for advice from a qualified military defense attorney who can evaluate the specific facts and command, service, and jurisdictional circumstances involved.
Reading this article, or contacting any website on which it appears, does not create an attorney-client relationship between the reader and any law firm, attorney, or author. Every court-martial, nonjudicial punishment action, administrative separation, and security-clearance matter turns on its own facts, the charged articles, the convening authority, the service branch, and the evidence, and outcomes vary widely from one case to another.
Military law also changes over time. The Military Justice Act of 2016 (effective January 1, 2019) and subsequent National Defense Authorization Acts renumbered and rewrote many punitive articles, revised the Article 32 preliminary hearing, and altered sentencing, clemency, and appellate procedures. Statutes, regulations, executive orders, the Manual for Courts-Martial, and decisions of the service Courts of Criminal Appeals and the Court of Appeals for the Armed Forces may have been amended, superseded, or reinterpreted after this article was written, and article numbers or procedures cited here may have changed.
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