A criminal conspiracy is generally a partnership formed to commit a crime or crimes. A criminal conspiracy exists when two or more persons form an agreement to violate a law that includes criminal penalties, and then take one or more steps designed to accomplish the goal of the conspiracy.

Federal and state statutes make criminal conspiracies illegal for two primary purposes: (1) to help combat the powerful forces created when two or more people collaborate to commit a crime; and (2) to allow criminal prosecutors (state and federal) to prosecute persons who play a role in planning a crime but who are not involved in the physical acts taken to complete the underlying crime.

For example, under federal law, if two or more persons conspire either to commit any offense against the United States, or to defraud the United States, or any agency of the United States in any manner or for any purpose, and one or more of such persons do any act to accomplish the objective of the conspiracy, each of the conspirators may be fined under and imprisoned for up to five years. See 18 U.S.C. §371. And most states have statutes (usually located in the penal or criminal code) that make criminal conspiracies a crime and include significant punishment upon conviction.

In Missouri, criminal conspiracy is defined under Missouri Revised Statutes Section 564.016. It occurs when two or more persons agree to engage in conduct that constitutes a crime, and at least one of them commits an overt act in furtherance of the agreement. The state of Missouri recognizes the seriousness of collaborative efforts to commit crimes and provides legal mechanisms to prosecute not only those who carry out the criminal acts but also those involved in the planning stages. The punishment for conspiracy in Missouri varies depending on the nature of the crime that the conspirators intended to commit, with penalties increasing if the intended crime is a felony. This aligns with the federal law under 18 U.S.C. §371, which also criminalizes conspiracy to commit any offense against the United States or to defraud the United States, with the possibility of fines and imprisonment for up to five years. Both state and federal laws reflect the dual objectives of disrupting the collective power of individuals working together to commit crimes and enabling the prosecution of individuals involved in the preparatory phases of criminal activity.