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 Virginia, criminal conspiracy is defined as an agreement between two or more persons to commit a criminal act or to accomplish a legal act by unlawful means. The crime of conspiracy in Virginia requires not only that the conspirators agree to commit a crime but also that at least one of them performs an overt act in furtherance of the conspiracy. This is in line with the general principle of conspiracy law, which aims to deter collaborative criminal activity and to hold accountable those who contribute to the planning and preparation of crimes, even if they do not participate in the actual commission of the crime. Under Virginia law, the penalties for conspiracy depend on the nature of the crime that the conspirators agreed to commit. For example, if the conspiracy involves a felony, the punishment for conspiracy will also be a felony, typically one level lower than the crime conspired to be committed. This is consistent with federal law, such as 18 U.S.C. §371, which allows for the prosecution and punishment of individuals involved in conspiracies against the United States or to defraud the United States, with penalties including fines and imprisonment.