On April 7, 2022, the Court of Justice of the European Union (CJEU) issued a preliminary ruling in United Airlines, clarifying the territorial scope and upholding the applicability of the Air Passenger Regulation in relation to connecting flights departing from an EU airport, even when the second leg of the flight takes place outside of the European Union. A decade after one of the most high-profile cases on the extraterritorial reach of EU law concerning the inclusion of global aviation emissions in the EU emissions trading system (ETS) (Air Transport Association of Americas), United Airlines brought to light its lasting significance and its extension to a different aspect of air transport concerning passenger rights.

As the gatekeeper of international law, the CJEU determines the effects not only of international agreements but also decisions of compliance review bodies. This article analyses the Court's engagement with rulings of the WTO dispute settlement bodies (DSB) and findings of the Aarhus Convention Compliance Committee (ACCC). These case studies demonstrate the varied toolkit used by the CJEU to forge relationships with external regimes, while maintaining the EU's autonomy. The CJEU considers DSB reports and ACCC findings selectively and implicitly, demonstrating a qualified openness to international law and a reluctance to engage in a meaningful dialogue with international quasi-judicial bodies.

When courts are faced with questions regarding the territorial scope of internal legislation, they are required to engage with controversial issues pertaining to the permissible boundaries of regulatory reach, which go beyond traditional conceptions of state sovereignty and non-intervention on which the functioning of courts is normally based. This Article examines the role of the Court of Justice of the European Union (‘CJEU’) in reviewing the legality and interpretation of the extraterritorial reach of EU environmental law, including animal welfare. It assesses the extent to which judicial review by the CJEU serves as a transnational mechanism for addressing legitimacy concerns raised by the unilateral exercise of EU regulatory power beyond EU borders.