Yes, the prosecution can introduce evidence of a service member’s prior, uncharged misconduct during the sentencing phase of a court-martial to argue for a harsher sentence, but only if they follow strict procedural rules. This type of evidence is considered “aggravating evidence” and is used to show the panel members that the convicted offense is part of a larger pattern of bad behavior, which might warrant a more severe punishment.
The most critical procedural requirement is notice. Under the Rules for Courts-Martial, the prosecutor must provide the defense with timely, written notice before the trial begins of their intent to introduce any evidence of uncharged misconduct at sentencing. This notice must be specific, detailing the nature of the uncharged misconduct they intend to present. This rule prevents the defense from being ambushed at sentencing with a host of new allegations they are not prepared to rebut.
If the prosecution provides proper notice, they can present the evidence at sentencing. This often involves calling witnesses to testify about the prior bad acts. The defense attorney has the right to cross-examine these witnesses and to present their own evidence to rebut the allegations of uncharged misconduct. The panel members will then weigh this evidence when determining an appropriate sentence. If the prosecutor fails to provide proper notice, the defense attorney will object, and the judge must exclude the evidence.