The Legality of Omnibus Legislation Under EU Law: A Preliminary Analysis of Omnibus I Simplification Directive of CSRD and CSDD and its Legal Consequences on the EU Legal Order

This paper provides a preliminary analysis of the legal issues arising from the European Union's use of the Omnibus as the privileged legislative technique to 'simplify' its existing regulatory framework. While the EU has used this method occasionally, it was traditionally reserved for technical consolidation. Therefore, the EU's novel deployment of omnibus legislation to 'simplify' its rules, by substantively amending existing legislation across multiple domains, represents a fundamental departure from established EU lawmaking that raises serious questions of legality. The shift is not merely one of scale but of constitutional function: the Omnibus has migrated from being an occasional administrative convenience to becoming the preferred vehicle for implementing a comprehensive deregulatory agenda while bypassing procedural integrity. Using the proposed Omnibus Simplification Directive (amending the Corporate Sustainability Reporting Directive-CSRD and Corporate Sustainability Due Diligence Directive-CSDDD) as the primary case study, this paper argues that while omnibus legislation is not per se incompatible with EU law, its deployment as a systematic mechanism to pursue its simplification agenda conflicts with EU core constitutional principles. The Omnibus I exemplifies this conclusion insofar as its Simplification Directive's proposal violates the principle of proportionality under Article 5(4) TEU and undermines the constitutional architecture of evidence-based, participatory lawmaking enshrined in Article 11 TEU and Article 296 TFEU. As the EU prepares more Omnibus packages, the question of whether this failure represents an isolated deviation subject to correction or the inauguration of a new constitutional normal characterized by constitutional drift remains to be determined. That determination lies not with legal analysis but with political choice, a choice the EU legislature must now make, mindfully and deliberately, understanding that its implications will extend far beyond the immediate measures under consideration. To remedy such a risk, this paper suggests constraining the use of the Omnibus within the boundaries of a dedicated regime, aimed at ensuring its compatibility with the EU legal order.