Theresa May faced embarrassment over her Brexit policy today when her own officials contradicted her stance over the European Court of Justice's future role.

As the Brexit department published a key negotiating paper on the role of the Luxembourg-based court, the Prime Minister insisted that “when we leave the EU we will be leaving the jurisdiction of the ECJ”.

But in an official briefing to journalists at almost the same time, Whitehall officials made it clear that the ECJ could still have supremacy over Britain's courts during the transition period following Brexit in March 2019.

They said an independent body that will arbitrate over post-Brexit disputes between the EU and the UK must be in place before the ECJ's jurisdiction in the UK can be ended, and there is no guarantee that the arbitration service will be ready by the withdrawal date. Click here for a full explainer on who will have the final say: British or European judges.