1 An agreement between two or more people to behave in a manner that will automatically constitute an offence by at least one of them (e.g. two people agree that one of them shall steal while the other waits in a getaway car). The agreement is itself a statutory crime, usually punishable in the same way as the offence agreed on, even if it is not carried out (see inchoate). Mens rea, in the sense of knowledge of the facts that make the action criminal, is required by at least two of the conspirators, even if the crime agreed upon is one of strict liability. One may be guilty of conspiracy even if it is impossible to commit the offence agreed on (for example, when two or more people conspire to take money from a safe but, unknown to them, there is no money in it: see also R v Shivpuri  2 All ER 334). A person is, however, not guilty of conspiracy if the only other party to the agreement is his (or her) spouse. Nor is there liability when the acts are to be carried out in furtherance of a trade dispute and involve only a summary and nonimprisonable offence. Incitement to conspire and attempt to conspire are no longer crimes.
Some forms of criminal conspiracy still exist at common law. These are now limited to: (1) conspiracy to defraud (e.g. to commit fraud, theft, obtain property by deception, or infringe a copyright) or to cause an official to act contrary to his public duty; (2) conspiracy to corrupt public morals (see corruption of public morals); and (3) conspiracy to outrage public decency (this might include an agreement to mount an indecent exhibition).
2 A conspiracy to injure a third party is a tort if two or more people act together to cause loss to that party. For lawful means conspiracy intention to injure must be the predominant purpose, rather than protection of one's own financial or trade interests. Unlawful means conspiracy requires a shared intention of using “unlawful means” to cause loss to the third party. In this context “unlawful” includes committing a crime, as well as a wrong actionable in civil law (Total Network SL v Revenue and Customs Commissioners  UKHL 19,  2 WLR 711).