Private prosecutions are permitted in the United Kingdom. They are governed by different rules in the different jurisdictions.
England and Wales
In the early history of England, the victim of a crime and his family had the right to hire a private attorney to prosecute criminal charges against the person alleged to have injured the victim. In the 18th century, prosecution of almost all criminal offences was private, usually by the victim.
In England and Wales, the Crown Prosecution Service (CPS) is the primary prosecuting authority with a discretionary power to take over any private prosecution. The CPS must apply a two part test of sufficiency of evidence and public interest before making a decision to take it over for the public good or leave it as a private prosecution.
The CPS can also prevent a private prosecution from continuing by taking it over and then discontinuing it. The CPS will do this only where there is not enough evidence to make a proper case or where a prosecution is against the public interest or where a prosecution could cause an injustice. In reaching this decision, it must balance the public good against a duty to preserve an individual's right to prosecute under the Prosecution of Offences Act 1985.
When taking over any private prosecution, the CPS may direct the police to conduct more investigation. The intention of this was to ensure the best available evidence was placed before the court, as further trials were generally excluded by the double jeopardy rule. The latter rule was abrogated in certain circumstances of "new and compelling evidence", and for a limited range of the most serious offences such as rape, armed robbery and murder, by the Criminal Justice Act 2003.