Only one overt act has to be proven. The government does not have to prove that the conspiracy succeeded or was achieved. There must be proof, however, that a second conspirator with criminal intent existed. Whether there is a single conspiracy, multiple conspiracies, or no conspiracy at all is ordinarily a factual matter for the jury to determine. A multiple conspiracy instruction should be provided if on the evidence adduced at trial, a reasonable jury could find more than one such illicit agreement, or could find an agreement different from the one charged.
Specific intent is preferred.
Withdrawal is not an affirmative defense if the conspiratorial agreement has already been made.