US Supreme Court Smith v. United States 11-8976

Decision here.

   Calvin Smith was a member of an organization that sold drugs (specifically crack, cocaine, heroin, and marijuana) in Washington, D.C.  In furtherance of the drug trade, members of the organization committed at least 31 murders and other violent crimes.  Smith (and several others) were eventually charged with conspiracy to distribute, RICO conspiracy, and murder.  They were convicted.

   At the time, Smith had been in prison for 6 years for something else.  Conspiracy has a 5 year statute of limitations, so Smith had unsuccessfully moved to dismiss those charges.  He was convicted anyway, based on a finding that the conspiracy had continued without him, and based on insufficient evidence that he had actually abandoned that conspiracy.  Smith appealed.

   The Supreme Court explained that conspiracy is a continuing offense, meaning that once a conspiracy has begun the conspirators are continuously committing the crime until either the conspiracy ends or they abandon the conspiracy.  Abandoning the conspiracy is an affirmative defense.  To show abandonment, a defendant has to demonstrate that he took actions that were at odds with the continuation of the conspiracy, and that he communicated his abandonment to his fellow conspirators (or at least tried to).  Abandonment must be unequivocal, or it doesn't count.

   In this case, Smith showed no such thing.  On the other hand, the government never presented evidence to prove that he hadn't abandoned the conspiracy.  But they didn't have to; all the prosecution had to prove was the elements of the offense.  The burden of proving an affirmative defense is on the defendant.  Smith's conviction was affirmed.

   Actually, the court gets pretty melodramatic about affirming his conviction:

"Having joined forces to achieve collectively more evil

than he could accomplish alone, Smith tied his fate to that

of the group. His individual change of heart (assuming it

occurred) could not put the conspiracy genie back in the

bottle. We punish him for the havoc wreaked by the unlawful 

scheme, whether or not he remained actively involved. It is his

 withdrawal that must be active, and it was his burden to show that."