Modern conspiracy is a vague offense. Basically a mental offense, it consists of a meeting of minds with wrongful intent. The object of agreement must be commission of an unlawful act or commission of a legal act by illegal means. See, MPC § 5.03(1).
Concert of action makes an offense more dangerous to society and harder to prevent than when it is committed singly. The potential for harm is so much greater, that conspirators merit punishment even if the object of agreement is never realized. Therefore, this doctrine fills the gap between derivative liability and principal liability, while also allowing for additional punishment when an offense is actually committed.
Conspiracy is unique to the common law; it is not found in civil law countries. Rather, they allow for greater punishment when an offense is planned or committed in concert.
b. Civil and Criminal Conspiracy
Because civil courts are not required to strictly construe statutes as criminal courts must, the doctrine of civil conspiracy is more expansive than its criminal counterpart. This occasionally carries over into criminal doctrine. Consequently, criminal conspiracy has been more liberally developed than most criminal offenses.