In response to the European Commission’s unexpected decision on 9 April 2024 to indefinitely postpone the publication of the first draft of the European Union Space Law (EUSL), this article takes a critical look at the EU’s competence under the Treaty of the Functioning of the European Union (TFEU) and Treaty of the European Union (TEU) to establish an EUSL that seeks to harmonize the national space laws of the Member States in the space security, safety, and sustainability domains. This article specifically examines the complexities around the Union’s competence to adopt space legislation in Articles 4(3) and 189 TFEU as one of the possible factors explaining the delay. It does this by analysing the legal foundations on which the EU has historically relied to pass space legislation and harmonize national laws. The article aims to address the concerns Member States may have regarding whether the Union must depend on its ‘space competence’ in Article 189 TFEU to achieve its security, safety, and sustainability objectives or if there is legal precedent allowing it to use a mix-and-match approach of its various competencies under the TEU and TFEU. The article concludes that the Union is competent to adopt an EUSL and suggests that it could employ various binding and non-binding strategies by relying on its competencies in overlapping domains, including inter alia, Articles 11, 114, 115, 167, 170–173, and 191–193 TFEU.