This chapter offers a comprehensive analysis of the case law of the Court of Justice concerning the principle of abuse of Union law. By examining the most significant judgments in chronological order, it demonstrates that while the development of the principle has been gradual, and at times uneven, it has ultimately led to a coherent and logically structured doctrine. The case law is divided into three phases: (a) the foundational period beginning with the Van Binsbergen ruling, (b) a phase of more structured development, initiated by the Emsland-Stärke ruling, and (c) the consolidation stage, marked by the Cussens ruling in 2017. The analysis culminates in a clear picture of the principle as it has progressively taken shape within the Union legal order.