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 New Mexico, criminal conspiracy is defined as an agreement between two or more persons to commit an unlawful act or to accomplish a lawful end by unlawful means. The agreement itself is considered a crime, separate from the crime that is the object of the conspiracy. Under New Mexico law, for a person to be convicted of conspiracy, it is not necessary for the person to have committed any overt act in furtherance of the conspiracy; the agreement alone can be sufficient. However, if an overt act is committed, it can be used as evidence of the existence of the conspiracy. The penalties for conspiracy in New Mexico depend on the nature of the crime that is the object of the conspiracy, with the punishment typically being one grade less severe than the most serious offense that is the object of the conspiracy. This is in line with the dual purposes of conspiracy laws: to disrupt the collaborative effort to commit crimes and to allow for the prosecution of those involved in the planning stages of criminal activities. At the federal level, as per 18 U.S.C. § 371, a conspiracy to commit an offense against the United States or to defraud the United States carries a penalty of fines and imprisonment for up to five years. Both state and federal laws reflect the seriousness with which the legal system treats criminal conspiracies.