Solidarity as a Fundamental Principle of EU Law

This article examines the principle of solidarity in the EU legal order by tracing the evolving contours of its meaning and operation in recent and emerging jurisprudence. It argues that interpreting solidarity through the lens of its underlying drivers (functional, axiological and identity based) offers a conceptually coherent account of its normative scope and boundaries. Solidarity has largely assumed an instrumental character, oriented towards securing the effective operation and systemic stability of the Union and its legal architecture. Yet the principle now stands at a transformative juncture, where a functional rationale no longer suffices to explain how it takes effect. Through instances that defy a purely instrumental logic, the article reconceptualises solidarity as a bearer of shared values and collective identity. This reframing is not only a matter of candour but indispensable for conceptual clarity and for engaging more directly with the constitutional stakes of sovereignty and belonging.