General principles of international law (GPIL) occupy a central but underexplored position in the European Union’s legal order. Despite their acknowledged role in international law, the definition, origin, and functions of GPIL remain contested. This article examines the interaction between GPIL and the EU legal system, with particular attention to the practice of the Court of Justice of the European Union (CJEU). It first situates GPIL within the EU’s constitutional framework, highlighting their ambiguous legal status. It then explores how the CJEU has relied upon, adapted, or resisted GPIL, both as sources of inspiration for general principles of EU law (GPEU) and as constraints within the EU’s autonomous legal order. While instances of reluctance or resistance reveal the Court’s concern for safeguarding EU autonomy, GPIL continue to provide interpretative guidance, systemic coherence, and bridges between EU and international law. The analysis ultimately demonstrates that the EU’s engagement with GPIL contributes to both the development of its own legal order and the broader coherence of international law.
Kassoti et al. (Tue,) studied this question.