The UK Supreme Court's decision in Belhaj v Straw defined foreign affairs non-justiciability and unearthed its constitutional foundations. However, two decisions since Belhaj—High Commissioner for Pakistan v Prince Muffakham Jah and The Law Debenture Trust Corpn plc v Ukraine—have called Belhaj into doubt, narrowing non-justiciability to give effect to ordinary private law rights. This article analyses these decisions and argues that their general approach of subjecting issues involving transactions between sovereign States to private international law's framework is desirable, because the constitutional foundations of non-justiciability identified in Belhaj are shaky. Yet, it is suggested that private international law itself may require courts to exercise judicial restraint on these issues, given its goal of upholding the efficient resolution of international disputes in appropriate fora.

This article explores traditional conceptions of non-justiciability in British Courts in honour of Francis Mann. It highlights the move by domestic courts away from traditional ‘no-go’ areas towards a more nuanced and balanced understanding of the respective roles and competences of the executive and the judiciary; and sees this as a not unfavourable development in an era when domestic recourse is often the only practicable means by which an individual, as opposed to a State, may obtain redress for alleged misconduct on the international plane.