Commissioner of Police for the Metropolis and Others, Ex Parte Pinochet

Factual and Procedural Background

Country A sought the extradition of the Defendant, a former head of state of Country C, who was present in Country B for medical treatment. Country A alleged that, while leader of Country C (1973–1990), the Defendant was responsible for widespread murder, torture and hostage-taking both within Country C and abroad.

Acting on an international arrest request, a magistrate in Country B issued two provisional warrants under the Extradition Act 1989. The second warrant covered allegations of torture, conspiracy to torture, hostage-taking, conspiracy to take hostages and conspiracy to murder. The Defendant applied for habeas corpus and judicial review. A Divisional Court quashed the warrants, holding that as a former head of state the Defendant enjoyed immunity ratione materiae. Country A, through its prosecuting authority, appealed to the Supreme Court of Country B (the “House of Lords”). During the appeal the scope of the charges expanded and a formal extradition request was served. The House of Lords was required to rehear the matter after its first decision was set aside for procedural irregularity.

Legal Issues Presented

1. Whether the conduct alleged constituted “extradition crimes” under the Extradition Act 1989—specifically, whether the double-criminality rule required the conduct to have been criminal in Country B at the time of commission or only at the time of extradition request.
2. Whether a former head of state enjoys immunity ratione materiae from arrest and extradition in Country B for acts of torture and related crimes allegedly committed while in office.

Arguments of the Parties

Plaintiff’s Arguments (Country A)

• The double-criminality rule is satisfied if the conduct is an offence in Country B at the date of the extradition request, irrespective of its status when committed.
• Torture is an international crime attracting universal jurisdiction; the Torture Convention, incorporated by section 134 of the Criminal Justice Act 1988, removes any immunity for former heads of state in respect of official torture.
• Immunity ratione materiae cannot shield international crimes such as systematic torture and related conspiracies.

Defendant’s Arguments

• The double-criminality rule requires the conduct to have been an offence in Country B when it occurred; many allegations pre-date section 134 of the 1988 Act and therefore are not extradition crimes.
• All acts alleged were performed in the Defendant’s official capacity; under customary international law a former head of state retains immunity for such acts.
• The Torture Convention does not expressly waive state immunity; any waiver must be express under international law.

Table of Precedents Cited

Court’s Reasoning and Analysis

Double-criminality. The majority held that section 2 of the Extradition Act 1989 looks to the law in Country B at the date of the conduct. Consequently, torture offences became extradition crimes only after 29 September 1988, when section 134 of the Criminal Justice Act 1988 entered into force. Most allegations pre-dating that moment therefore fell outside the statute.

Narrowing of charges. After applying the double-criminality test, only three categories of allegation remained extraditable: (i) conspiracy to torture between 29 September 1988 and 11 March 1990, (ii) specific acts of torture during that period, and (iii) certain conspiracies to murder formed in Country A.

Immunity. The Court distinguished between immunity ratione personae (absolute, for a serving head of state) and ratione materiae (for former officials acting in an official capacity). It held that the Torture Convention, incorporated domestically by section 134, created universal jurisdiction over official torture and was incompatible with any claim of immunity for that conduct. Once Country C and Country B ratified the Convention, the Defendant could no longer invoke state immunity in respect of post-1988 torture.

The immunity defence succeeded, however, for surviving allegations of conspiracy to murder, because murder did not carry the same universal jurisdiction features as torture under the Convention framework.

Holding and Implications

Appeal Allowed in Part. Extradition proceedings may continue only on charges of torture and conspiracy to torture allegedly committed after 29 September 1988; all other allegations are barred either because they are not extradition crimes or because immunity applies.

Implications: The decision sharply limits former heads of state from claiming immunity for official torture once a state has adopted the Torture Convention in domestic law. It also clarifies the temporal application of double-criminality under the Extradition Act 1989. The Secretary of State must reconsider whether to issue a fresh authority to proceed in light of the reduced list of charges; no new precedent was set on conspiracy to murder.