Habeas corpus, justiciability and foreign affairs

The prerogative writ of habeas corpus historically served the important constitutional function of allowing people who were imprisoned by the executive government to challenge the legality of their detention. The central requirement of the writ, which is that those who detain a person must prove the lawfulness of that detention, long provided applicants for the writ with a greater scope to challenge official decisions than was possible in an application for judicial review. This aspect of habeas corpus has assumed renewed importance in modern 'transnational' applications for the writ (in which the applicant seeks habeas corpus against a government or official who is not the custodian of the applicant but may be able to exert influence over another government which has detained the applicant). This article argues that these 'transnational' applications for habeas corpus suggest that the writ remains an important constitutional protection that should be preserved. It also argues that, whereas the requirements of habeas corpus have remained relatively constant, in recent decades, the principles of judicial review have shifted into closer alignment with them and the courts have become more willing in that context to grapple openly with questions of foreign relations or other politically sensitive issues.