Conspiracy

Conspiracy is an agreement to commit a crime. Sometimes a conspiracy statute will also require an additional element: overt act. Conspiracy is its own crime. That is, if A and B agree to rob a bank, at that moment they have committed conspiracy to bank robbery even if they do not rob the bank. If they do rob the bank, they can be convicted and sentenced separately for both the conspiracy charge and the bank robbery charge.

Conspiracy differs from attempt in a few ways. First, conspiracy can reach and criminalize a defendant's conduct earlier in the preparation than attempt. The agreement is the crime, so it can be farther removed from the crime than attempt. Second, a person cannot be convicted and separately sentenced for attempted murder and murder. He can be convicted for both conspiracy to murder and, if he succeeds, murder.

Conspiracy also differs from aiding and abetting. They are sometimes confused because aiding and abetting is also called "complicity," which sounds like "conspiracy." They are also similar because they both involve two or more people working together to commit a crime. 

But here is how they differ. First, the words. Complicity means associates who work together; conspiracy means to breath together, that is, to whisper, meaning, to agree to commit a crime. Second, aiding and abetting (complicity) requires that the actual crime occur. Complicity is not its own crime. It is a theory or mechanism by which we hold the accomplice liable for the actual crime. Hicks was charged with murder, not complicity to murder. He was charged with murder via the mechanism of aiding and abetting. Complicity is not its own crime.

Conspiracy is a crime even if the target crime never occurs. 

Finally, a word on mens rea. The mens rea for conspiracy is purpose or intent--namely, intent to commit the target crime. But of course this purpose is implicit in the idea of an agreement. If two people agree to commit a crime, they naturally intend to commit that crime.