[simonh]

Every international treaty and trade agreement includes an adjudication process in case of disputes. The adjudication panel has oversight of interpretation of the treaty, not individual National course, for very obvious reasons. The ECJ is the transnational adjudication panel for the EU.

There’s nothing particularly special about the concept. It’s no different in principle than the WTO dispute resolution process, the International Court of Justice at the UN, or any number of other international arbitration, dispute resolution or treaty enforcement mechanisms past or present. All of those have the agreed power yo adjudicate on whether domestic UK laws are in violation of our treaty agreements.