When unrelated offenses are joined for a single court-martial, the defense may move to sever them so they are tried separately. Whether that motion succeeds depends on a demanding standard. Military law strongly favors trying all known charges together, and a court-martial will sever charges only when keeping them joined would produce a manifest injustice. This article explains how a military judge evaluates a severance motion, the governing rule, the controlling test, and the standard of review that applies on appeal.
The strong preference for joinder
The starting point is a policy preference for a single trial. The Rules for Courts-Martial authorize the referral of two or more offenses to one court-martial, and the guidance accompanying the rules states that ordinarily all known charges against an accused should be tried together. Joinder in the military is in fact more permissive than in federal district court. This preference exists for reasons of efficiency and finality, sparing witnesses, panels, and the system the burden of repeated trials. Because of this preference, an accused who wants charges tried separately bears the burden of justifying a departure from the norm.
The governing rule and its standard
A motion to sever offenses is brought under Rule for Courts-Martial 906(b)(10). That rule does not allow severance whenever separate trials might be more convenient or more favorable to the accused. It permits severance only to prevent a manifest injustice. The phrase manifest injustice sets a high bar. The accused must show that trying the offenses together would do more than create some risk or some disadvantage. It must threaten the fundamental fairness of the trial. When that showing is made, the rule requires the military judge to grant severance. The decision is therefore mandatory once manifest injustice is established, but the threshold for establishing it is steep.
The controlling test from United States v. Giles
The Court of Appeals for the Armed Forces addressed the standard in United States v. Giles, 59 M.J. 374 (2004). In that case the court applied a three-part inquiry to determine whether denying severance failed to prevent a manifest injustice and deprived the accused of a fair trial. The inquiry asks, first, whether the evidence of one offense would be admissible proof in the trial of the other offense. Second, it asks whether the military judge gave the panel a proper limiting instruction directing it to consider the evidence of each offense separately. Third, it asks whether the findings reflect an impermissible crossover, meaning whether the verdicts show that the panel improperly used evidence of one offense to convict on another.
These three considerations work together. If the evidence of each offense would be mutually admissible in a separate trial of the other, the risk of unfair spillover is low, because the panel would hear the same evidence even with severance. If a proper limiting instruction was given, the law presumes the panel followed it and kept the offenses distinct. And if the findings themselves do not show that the panel blurred the offenses, the joinder did not produce the kind of prejudice that severance is meant to prevent. When all three point in the government’s favor, denying severance does not create manifest injustice. When they point the other way, particularly where dissimilar offenses share no evidentiary overlap, no limiting instruction was given, and the verdicts suggest crossover, the failure to sever can amount to reversible error. In Giles itself the court found that the military judge erred in the way the severance question and related matters were handled and that the error prejudiced the accused.
Why unrelated offenses raise particular concern
The concern is sharpest when the joined offenses are genuinely unrelated. Where charges are similar in character or arise from connected facts, evidence of one often is admissible in the trial of the other, which reduces the danger of joinder. Unrelated offenses are different. The evidence supporting one may have nothing to do with the other, so trying them together can expose the panel to information it would never hear in a separate trial. That raises the danger that the panel will reason that a person who committed one offense probably committed the other, or will aggregate the evidence into a general impression of bad character. This is precisely the spillover that the manifest injustice standard and the Giles test are designed to guard against. The more truly unrelated the offenses, the more weight the first part of the test carries, because mutual admissibility is unlikely.
The standard of review and the prejudice requirement
A military judge’s ruling on a severance motion is reviewed for abuse of discretion. This is a deferential standard. To prevail, the accused must show that the denial of severance caused actual prejudice that prevented a fair trial. It is not enough to argue that separate trials might have offered a better chance of acquittal. The law tolerates the ordinary disadvantages of a joint trial. What it will not tolerate is a joinder that, through evidentiary spillover and the absence of safeguards, deprives the accused of a fair determination on each charge. The abuse of discretion standard means appellate courts will uphold a denial of severance unless the record shows the judge’s ruling fell outside the range of reasonable choices and worked actual prejudice.
Practical guidance for the defense
A defense motion to sever unrelated offenses is most persuasive when counsel can show that the evidence of the offenses is not mutually admissible, that joinder will expose the panel to prejudicial information it would not otherwise hear, and that there is a real risk the panel will use evidence of one offense to convict on another. Counsel should frame the argument around the Giles factors, emphasize the absence of evidentiary overlap between truly unrelated charges, and explain why a limiting instruction would not cure the spillover. Because the standard is manifest injustice and the review is for abuse of discretion, the motion must be grounded in concrete prejudice rather than mere preference for separate trials.
Conclusion
Defense motions to sever unrelated charges are evaluated against a high standard. Military law favors trying all known offenses together, and Rule for Courts-Martial 906(b)(10) permits severance only to prevent a manifest injustice. United States v. Giles supplies the controlling three-part test, which examines mutual admissibility of the evidence, the presence of a proper limiting instruction, and whether the findings reflect impermissible crossover. A military judge’s ruling is reviewed for abuse of discretion, and the accused must show actual prejudice that prevented a fair trial. Severance is most attainable when offenses are genuinely unrelated and their evidence does not overlap, because that is where the danger of spillover, and thus of manifest injustice, is greatest.
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.
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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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