Following-up on the many academic analyses of strategic autonomy over the past decade, this special issue aims to take a more comprehensive perspective on ‘security’ by analysing the notion of strategic autonomy from a legal vantage point. After two more general contributions – on the role of the Court of Justice of the European Union and on the ‘supranationalization’ of security despite the key role of EU Member States in this area – the focus turns on specific policy areas. Subsequent contributions thus address strategic autonomy in the context of EU defence-industrial spending, sanctions, data autonomy, energy and investment and economic measures. Together, these contributions highlight different dimensions of the challenges the EU is currently facing. The question that is central to this Introduction –and to the special issue as whole – is to identify and shed light on the important legal contours of an essentially political concept. strategic autonomy, comprehensive security, EU external relations, security and defence, EU competences