On 26 July 2017, the Conseil constitutionnel ruled upon the compatibility of an EU (mixed) agreement with the French Constitution. Its decision, which concerned the EU-Canada Comprehensive Economic and Trade Agreement (CETA), clarifies, from a national constitutional law perspective, the room of manoeuvre of the national judge when controlling EU acts which also happen to be acts of the Member States. The necessity to combine EU law with French constitutional law when monitoring this specific category of international commitments of the French Republic results in a very narrow margin of manoeuvre for the judge. In the end, the Conseil constitutionnel considers CETA to be compatible with the Constitution of the French Republic.