The law

Dual criminality

Dual criminality means the conduct must be a crime in both the requesting and the requested state, usually above a minimum level of seriousness.

• The European Convention on Extradition covers offences punishable under the laws of both parties by at least one year of imprisonment, or at least four months where a sentence has already been imposed.¹
• In the UK, section 137 of the Extradition Act 2003 asks whether the conduct would be an offence punishable with 12 months or more if it had happened in the relevant part of the UK.²
• In the Pinochet case the House of Lords held that the conduct must be criminal under UK law at the date of the conduct, so torture abroad before 29 September 1988 was not an extradition crime.³

Sources

1. Council of Europe, European Convention on Extradition (ETS No. 24), Paris, 13 December 1957 (13 December 1957)
2. legislation.gov.uk (The National Archives), Extradition Act 2003, section 137 (Extradition offences: person not sentenced for offence) (27 October 2026)
3. House of Lords, Regina v. Bartle and the Commissioner of Police for the Metropolis and Others, Ex Parte Pinochet (judgment of 24 March 1999) (24 March 1999)