In its long-awaited judgment relating to Illumina’s acquisition of Grail, the European Court of Justice last week held that the European Commission acted ultra vires by asserting jurisdiction over non-reportable mergers under its expanded Article 22 EUMR referral policy introduced in 2021. The judgment removes the risk of EU Member States with merger control laws referring mergers to the Commission where the relevant national competition authority does not have jurisdiction to review under those laws. However, legal certainty has not been restored fully due to certain Member State’s own call-in powers, which may allow the Commission to continue reviewing below-threshold mergers following referrals from those Member States under Article 22 of the EU Merger Regulation.