Conspiracy under the Uniform Code of Military Justice is charged under Article 81. The statute makes it an offense for any person subject to the code to conspire with another to commit an offense under the code, where at least one conspirator performs an overt act to bring about the object of the agreement. A recurring defense theory arises when the accused says, in substance, that he agreed to do something but genuinely believed the plan was lawful. This article explains how that mistaken belief argument fits into the elements of conspiracy, where it can succeed, and where it usually cannot.
The elements the government must prove
To convict under Article 81, the prosecution must establish four things. First, that the accused entered into an agreement with one or more persons to commit an offense under the code. Second, that the agreement was made with the intent that the underlying offense be committed. Third, that while the agreement existed, at least one conspirator performed an overt act to effect its object. Fourth, that the accused knew of the agreement and voluntarily joined it. The mental state is demanding. Conspiracy requires a knowing and intentional agreement aimed at carrying out a specific offense. Mere knowledge of someone else’s plan, or passive presence, is not enough.
Because intent sits at the heart of the offense, a sincere and reasonable belief that the planned conduct was legal can attack the case at its most vulnerable point. The question is always whether that belief negates the specific intent the statute requires.
Mistake of fact versus mistake of law
Military law, like civilian criminal law, treats mistakes about facts very differently from mistakes about the law. A mistake of fact occurs when the accused is wrong about something in the world, for example believing the property he agreed to take already belonged to him. A mistake of law occurs when the accused understands the facts but is wrong about whether those facts amount to a crime.
The general rule is that ignorance of the law is not a defense. A service member who agrees to a plan, correctly understands what the plan involves, but assumes it is permissible, usually cannot escape liability merely by saying he did not know it was illegal. That is a classic mistake of law and it ordinarily fails.
The picture changes when the offense itself requires a specific intent or …