Accessory (legal term)

An accessory is a person who assists in the commission of a crime, but who does not actually participate in the commission of the crime as a joint principal. The distinction between an accessory and a principal is a question of fact and degree:

In some jurisdictions, an accessory is distinguished from an accomplice, who normally is present at the crime and participates in some way. An accessory must generally have knowledge that a crime is being, or will be committed. A person with such knowledge may become an accessory by helping or encouraging the criminal in some way. The assistance to the criminal may be of any type, including emotional or financial assistance as well as physical assistance or concealment.

The punishment tariff for accessories varies in different jurisdictions, and has varied at different periods of history. In some times and places accessories have been subject to lesser penalties than principals (the persons who actually commit the crime). In others accessories are considered the same as principals in theory, although in a particular case an accessory may be treated less severely than a principal. In some times and places accessories before the fact (i.e., with knowledge of the crime before it is committed) have been treated differently from accessories after the fact (e.g., those who aid a principal after a crime has been committed, but had no role in the crime itself). Common law traditionally considers an accessory just as guilty as the principal(s) in a crime, and subject to the same penalties. Separate and lesser punishments exist by statute in many jurisdictions.

In some situations, a charge of conspiracy can be made even if the primary offense is never committed, so long as the plan has been made, and at least one overt act towards the crime has been committed by at least one of the conspirators. For example, if a group plans on forging bank checks, and forges the checks but ultimately does not attempt to cash the checks, the group might still be charged with conspiracy due to the overt act of forgery. Thus, an accessory before the fact will often, but not always, also be considered a conspirator. A conspirator must have been a party to the planning of the crime, rather than merely becoming aware of the plan to commit it and then helping in some way.

A person who incites another to a crime will become a part of a conspiracy if agreement is reached, and may then be considered an accessory or a joint principal if the crime is eventually committed.

...
Wikipedia