Yes, questioning by a service member’s chain of command absolutely triggers the obligations of Article 31 if that service member is suspected of an offense. The UCMJ makes no distinction between a criminal investigator and a commander when it comes to the duty to provide rights warnings. Any person subject to the code who is acting in an official capacity must give the warning.
When a commander, First Sergeant, Platoon Leader, or any other superior questions a subordinate about suspected misconduct, the interaction is inherently official and coercive. The subordinate has a duty to obey lawful orders, and this creates a power dynamic where they may not feel free to refuse to answer. This is precisely the type of “subtle coercion” that Article 31 was designed to counteract.
Therefore, the moment a commander suspects a service member of a specific offense and begins to ask questions to elicit an incriminating response, the commander is legally obligated to stop and provide a full Article 31(b) rights advisement. This includes informing the service member of the nature of the accusation, their right to remain silent, and that anything they say can be used against them.
A common mistake made by commanders is believing they can have an “informal chat” to get to the bottom of an issue without triggering Article 31. The courts have consistently rejected this notion. If the purpose of the questioning is to investigate suspected criminal conduct, the rights advisement is mandatory. Any statement obtained by a commander in violation of this rule will be suppressed in a subsequent court-martial, potentially crippling any disciplinary action.