Solidarity has consistently played a pivotal role in the arguments presented before the Court of Justice of the European Union (CJEU). As a principle, value or concept, the idea of ‘solidarity’ offers an enticing avenue for parties seeking favourable interpretations of EU law. The notion of solidarity permeates various fields and areas of EU law, reflecting its partial legalization through its presence in the EU Treaties. The critical question that emerges is how and to what extent the CJEU should employ and interpret solidarity in its judgments. This article delves into the CJEU’s case law where solidarity has been scrutinized, ‘on trial’, revealing that the CJEU is now poised, with particular enthusiasm, to integrate solidarity into its reasoning, by explicit reliance upon it. By doing so, the CJEU aims to embed the logic of solidarity within specific areas of the EU legal framework. Consequently, this article explores how solidarity might influence different sectors of EU law and the potential ramifications for this development if the CJEU does not exercise sufficient caution.