Why the Illumina/Grail ECJ Ruling Is Redrawing EU Merger Control and Deal Risk

Legal Context and the Illumina/Grail Ruling

On 3 September 2024, the Court of Justice of the European Union (ECJ) in Illumina/Grail overturned prior EC guidance and held that Article 22 of the EU Merger Regulation does not permit national competition authorities (NCAs) to refer mergers to the European Commission where the NCA itself has no national jurisdiction over the transaction—that is, if the transaction is below both EU and national thresholds.

This decision removed a tool the European Commission had encouraged for addressing “killer acquisitions”—i.e. when large incumbent firms acquire small, nascent competitors before thresholds are met. The ECJ emphasised that thresholds are essential for legal certainty and predictability.

Rise of National Call-in Powers

In light of Illumina/Grail, EU member states have begun to legislate or amplify national “call-in” regimes so that NCAs gain power to require notification and review of below-threshold transactions where competitive impact is evident. These powers vary in scope, timing (pre- or post-closing), remedial powers (including divestment or annulment), and criteria for triggering review.

Examples include Denmark (since mid-2024), Italy, Hungary, Ireland, Latvia, Lithuania, Slovenia, Sweden with full call-in powers; meanwhile Netherlands, Belgium, Germany, Finland, Czech Republic among those considering or developing call-in regimes.

Case Study: Nvidia / Run:AI

Italy’s competition authority (Autorità Garante della Concorrenza e del Mercato, AGCM) used its call-in power in 2024 to bring Nvidia’s acquisition of AI start-up Run:AI, which did not meet EU or Italian thresholds, to EU EC review via Article 22. The EC cleared it unconditionally in December 2024. But Nvidia has challenged that acceptance of the referral, arguing the combination of loosely defined national call-in discretion and Article 22 referral violates legal certainty and other EU law principles.

France and Other Key Jurisdictions Evolving

France’s Competition Authority launched in January 2025 a public consultation offering three options: (1) introduce a call-in power based on qualitative and quantitative criteria; (2) mandatory notifications in cases involving firms with past merger control decisions, antitrust sanctions, or gatekeeper status under the DMA; or (3) rely on ex-post antitrust enforcement, e.g. under Article 101 or 102 TFEU. Stakeholders strongly favoured option 1.

Germany currently operates a transaction value threshold (TVT) regime, and its head has signalled openness to introducing call-in powers, especially for “killer acquisitions,” which may be poorly captured by TVT alone.

Strategic Implications and Open Questions

For M&A dealmakers, the evolving landscape means:

• Heightened pre-deal risk assessment: deals previously assumed safe due to falling below thresholds may now be subject to NCAs’ discretion or post-closing scrutiny. Documentation will need to anticipate potential remedies or divestment demands even in small-scale or local deals.
• Increased timing and process complexity: overlapping jurisdictions, varying national standards of “significant effect,” and different standstill or unwinding powers could lead to delays or even conflicting outcomes across EU states.
• Investment risk particularly in tech and innovation sectors or local markets where smaller targets may become competitive threats.

Open questions include whether the EU legislature will reform EUMR itself to incorporate a safeguard for below-threshold deals; whether full harmonization or mutual recognition of national call-in regimes will be feasible; how businesses will manage legal certainty if “call-in power” regimes diverge significantly across member states; and whether courts will further define limits of NCAs’ discretion to ensure consistency. The outcome of Nvidia’s challenge and France’s reforms will likely shape this trajectory.