Complicity is the participation in a completed criminal act of an accomplice, a partner in the crime who aids or encourages (abets) other perpetrators of that crime, and who shared with them an intent to act to complete the crime. A person is an accomplice of another person in the commission of a crime if they purpose the completion of a crime, and toward that end, if that person solicits or encourages the other person, or aids or attempts to aid in planning or committing the crime, or has legal duty to prevent that crime but fails to make an effort to prevent it properly.
Unlike attempt, solicitation, and conspiracy, which are crimes in and of themselves, complicity is not itself a crime but is a way of committing a crime. It also differs from an attempt, solicitation, and conspiracy in that it always depends on that crime having been completed (i.e., it is never inchoate.). Complicity does not require causation of the crime, merely participating in the commission of the crime. In cases where one is complicit because of a failure to act when one has a duty to act to prevent a crime, complicity differs from omission in that liability for complicity arises from the related to other perpetrators, whereas liability for omission arises from a duty relationship to the victim.
Common law traditionally distinguished between a "principal" perpetrator who is primarily responsible for a crime and an "accessory" perpetrator who is less responsible. However, modern approaches abandon this distinction, and "a person is legally accountable for the conduct of another when he is an accomplice of the other person in the commission of the crime".
For two persons to be complicit in a crime that does not involve negligence, they must share the same criminal intent; "there must be a community of purpose, partnership in the unlawful undertaking". An accomplice "is a partner in the crime, the chief ingredient of which is always intent". In crimes not involving negligence, there should be evidence that an accomplice had knowledge of the intention of their partner.
Common law
At common law, actors were classified as principals and/or accessories. Principals were persons who were present at the crime scene and participated in its commission. Accessories were persons who were not present during the commission of the crime but who aided, counseled, procured, commanded, encouraged, or protected the principals before or after the crime was committed. Both categories of actors were further subdivided. Principals in the first degree were persons who, with the requisite state of mind, committed the criminal acts that constituted the criminal offense. Principals in the second degree also referred to as aiders and abettors, were persons who were present at the scene of the crime and provided aid or encouragement to the principal in the first degree. Accessories were divided into accessories before the fact and accessories after the fact. An accessory before the fact was a person who aided, encouraged, or assisted the principals in the planning and preparation of the crime but was absent when the crime was committed. An accessory after the fact was a person who knowingly provided assistance to the principals in avoiding arrest and prosecution. It was eventually recognized that the accessory after the fact, by virtue of his involvement only after the felony was completed, was not truly an accomplice in the felony.
Types of assistance
To be deemed an accomplice, a person must assist in the commission of the crime by "aiding, counseling, commanding or encouraging" the principal in the commission of the criminal offense. Assistance can be either physical or psychological. Physical assistance includes actual help in committing the crime as long as the acts of assistance do not constitute an element of the offense. It also includes such things as procuring weapons to be used to commit the crime, or serving as a lookout during the commission of the crime, or providing protection from arrest or prosecution after the crime's commission. Psychological assistance includes encouraging the principal to commit the offense through words or gestures, or mere presence as long as the principal knows that the accomplice's purpose is present to provide assistance. It is not necessary that the accomplice's acts cause or contribute to the principal's committing the crime. In other words, the prosecution need not prove that the accomplice's acts were either a proximate cause or cause in fact of the crime.