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 South Dakota, criminal conspiracy is addressed under state law, specifically SDCL 22-3-8, which defines conspiracy as an agreement between two or more persons to commit a crime and requires that at least one of the conspirators performs an overt act in furtherance of the conspiracy. The state's approach aligns with the dual purposes of conspiracy laws: to dismantle the collaborative efforts to commit crimes and to enable the prosecution of individuals involved in the planning stages of criminal activities, even if they do not participate in the execution of the crime itself. Penalties for conspiracy in South Dakota vary depending on the crime that the conspirators agreed to commit, with the punishment often mirroring the severity of the underlying offense. At the federal level, 18 U.S.C. §371 criminalizes conspiracies to commit any offense against the United States or to defraud the United States, with potential fines and imprisonment of up to five years. Both state and federal laws reflect a commitment to preventing and penalizing collaborative criminal behavior.