The short answer is that physical assistance is not required. Article 78 of the UCMJ, which defines the offense of accessory after the fact, can be satisfied by verbal acts of concealment as well as by physical help. The statute reaches any conduct that receives, comforts, or assists an offender for the purpose of hindering apprehension, trial, or punishment, and that conduct does not have to be a physical act such as hiding a person or moving evidence. Lying to investigators, giving a false alibi, warning an offender, or otherwise using words to shield someone can supply the assistance element. Understanding why that is so requires looking carefully at what Article 78 actually requires.
What Article 78 is
Article 78, codified at 10 U.S.C. 878, makes it an offense to be an accessory after the fact. Unlike a principal, who commits or aids the underlying crime, an accessory after the fact becomes involved only after the offense is complete. The wrongdoing lies in helping the offender escape the consequences of a crime the accessory knows has already been committed.
The four elements
A conviction under Article 78 requires the government to prove four elements beyond a reasonable doubt.
First, that an offense punishable by the UCMJ was committed by a certain person. The principal offense must actually have occurred, although the principal need not have been charged or convicted for the accessory to be guilty.
Second, that the accused knew that the person had committed that offense. This is a knowledge requirement, and it is significant.
Third, that thereafter the accused received, comforted, or assisted the offender. This is the conduct element at the center of the present question.
Fourth, that the accused did so for the purpose of hindering or preventing the apprehension, trial, or punishment of the offender. This is the specific intent that gives the offense its character.
Why verbal concealment satisfies the assistance element
The third element uses the words “received, comforted, or assisted.” None of those words is limited to physical action. Assistance under Article 78 is not confined to acts designed to effect the escape or concealment of the principal. It also includes acts intended to conceal the offense itself. Spoken or written conduct can do exactly that.
Consider the common scenarios. A service member who, knowing a fellow member committed an assault, tells investigators that the offender was somewhere else at the time …