Conspiracy is one of the most frequently charged and little understood federal crimes. It generally involves two or more people agreeing to commit a federal offense, and one of the people doing something toward implementing the plan. There does not have to be any illegal act, written agreement, or other interaction, just evidence that the people involved were working together in some way to commit a crime sometime in the future.
Federal prosecutors often cast a wide net with conspiracy charges so they can accumulate additional evidence in other kinds of cases, such as drug distribution and fraud, and discover other possible offenses. One problem with this tactic is that individuals who have been even slightly involved with an alleged criminal act can be dragged into the case and punished severely.