Human rights bars and Article 3 ECHR

States bound by the European Convention on Human Rights may not extradite a person who faces a real risk of torture or inhuman or degrading treatment, and domestic courts must check compatibility with Convention rights.

The European Court of Human Rights says Article 3 bars extradition to a state where the person faces a real risk of inhuman or degrading treatment, which can include a grossly disproportionate sentence.¹
In Babar Ahmad and Others v UK (10 April 2012) the Court found no violation of Article 3 based on the length of possible US sentences for five applicants. In Sanchez-Sanchez v UK (2022) the Grand Chamber adopted an adapted approach for extradition cases.¹
Diplomatic assurances from the requesting state can avert a risk, according to the Court's factsheet.¹
In urgent cases the Court can indicate interim measures under Rule 39 to suspend a removal, and in Mamatkulov and Askarov v Turkey it held that states are obliged to comply with them.²
Section 87 of the UK Extradition Act 2003 requires the judge to decide whether extradition would be compatible with Convention rights, and to discharge the person if not.³
In October 2012 the UK Home Secretary withdrew the extradition order against Gary McKinnon, citing Article 3 and a high risk that he would end his life.⁴

Sources

European Court of Human Rights, Factsheet: Extradition and life imprisonment (April 2024)
European Court of Human Rights, Factsheet: Interim measures (March 2024)
legislation.gov.uk (The National Archives), Extradition Act 2003, section 87 (Human rights) (27 October 2026)
UK Parliament (Hansard), House of Commons Hansard, 16 October 2012, Home Secretary statement on extradition (16 October 2012)