A Matter of Measure: Proportionality of Penalties and the Soft Dialogue Among Courts in the EU

This paper analyses the role of the principle of proportionality of penalties in shaping the constitutional architecture of EU enforcement. Building on the recognition of direct effect to a particular manifestation of the proportionality requirement in NE judgment (C-205/20) by the Court of Justice of the European Union, the article explores how proportionality operates as a criterion for allocating powers between national trial and constitutional courts in fields falling within the notion of ‘criminal matter’. Particular attention is paid to the tensions arising from the hypothetical EU‑mandated disapplication of disproportionate sanctions, especially in light of domestic principles such as legality, separation of powers, and – most of all – equality before the law. Against this background, the paper uses the Italian Constitutional Court’s judgment no. 7 of 2025 as a lens to examine the systemic consequences of an expansive reading of proportionality and its direct effect. It argues that this interpretative amplification of proportionality’s effectiveness raises broader questions concerning the balance between decentralized judicial enforcement of the Charter and centralized constitutional coordination at national level.