Conspiracy is the concerted effort or act of committing the crime. Conspiracy is a specific intent crime and the common law requires two parties for a conspiracy charge. Both parties must have the same mens rea or “mutuality” (See State v. Hayes). The common law does not require an over act or a step beyond preparation for the crime; however, it does require a showing of when the agreement (or implied agreement) was actually formed.
Under conspiracy, a defendant can be held accountable for acts that exceed the defendant’s initial agreement. In Pinkerton v. United States, the court held the defendant liable for acts of co-conspirators that occurred “in the furtherance” of the conspiracy. Under this standard, the court looks from the point of view of the conspiracy and states that those acts which are “reasonably foreseeable consequences of the conspiratorial agreement.”
Note: This standard is different from the natural and probable consequences doctrine under felony-murder which viewed forseeability from the perspective of the defendant.
Defeat the purpose of the conspiracy
Under the common law, a defendant could not abandon the original conspiracy. Once the defendant entered the conspiracy, he was stuck. However, the common law did allow a defendant to withdraw from the reasonably foreseeable consequences (aka the Pinkerton crimes). In order to withdraw from these consequences, the defendant had to notify the co-conspirators of his withdrawal and the withdrawal had to be completed within a reasonable amount of time so that the co-conspirators could also withdraw before the commission of the crime.
MPC Conspiracy
Under the MPC Section 5.03, both parties do not need the same mens rea (no mutuality required). Because conspiracy is a specific intent crime, the defendant can only be charged with conspiracy, attempt, or solicitation. The state must choose one of the three.
Under the MPC Section 5.03(6), renunciation must be presented as an affirmative defense if the defendant “thwarted the success of the conspiracy.” This could include calling law enforcement with a reasonable amount of time so that the co-conspirators could also withdraw. The MPC essentially rejects Pinkerton because it allows the defendant to avoid the conspiracy charge as a whole instead of only avoiding the foreseeable consequences with an appropriate renunciation.