Michel Barnier | Martin Divisek/EPA Brussels will insist on ECJ in Brexit treaty, says Barnier EU negotiator says ‘the only frictionless relation with the UK would be a Norway Plus’ model.

HANNOVER, Germany — The European Union will insist that the Brexit agreement include the European Court of Justice providing permanent judicial oversight over future EU-U.K. relations, its chief Brexit negotiator said Monday.

"We need an agreement on governance and the role of the Court of Justice," Michel Barnier said in a speech at a reception held by the German engineering association VDMA at the Hannover Messe.

“Without an agreement on governance, there is no credibility of this treaty for stakeholders, for business," he added.

Barnier's comments are likely to be a nonstarter for Brexiteers, who have demanded that Britain completely leave the jurisdiction of the ECJ once the country quits the EU at the end of March next year. In her Mansion House speech last month, Prime Minister Theresa May said "the jurisdiction of the ECJ in the U.K. must end."

In February, the European Commission presented a draft withdrawal agreement that refers to a joint committee to oversee and implement the withdrawal agreement. According to that draft, the ECJ should have final say on future disputes that arise between the EU and U.K. and which could not be solved in that joint committee.

Barnier, in his speech on Monday, acknowledged that May has pledged to end the jurisdiction of the ECJ as well as to leave the EU's customs union. However, "with these red lines, the U.K. is closing doors," he warned.

Barnier also spoke of the need for "adequate enforcement" between the EU and U.K. to avoid being "undercut by unfair competition."

"There will be no ambitious partnership without common ground on competition and state aid, social and environmental standards, and guarantees against tax dumping," he said.

Focussing on trade matters, Barnier said "the only frictionless relation with the U.K. would be a Norway Plus" model. This, he said, means a partnership under which the U.K. would continue to apply EU laws and guarantee free movement, like Norway currently does, and also form a customs union with Brussels. Last week, Brussels rejected the U.K.’s two post-Brexit customs proposals to solve the Northern Ireland border issue.

"Norway Plus means … they have to change their red lines," the Brexit chief negotiator said. "This is the only frictionless model for the business to avoid controls. In all the other cases, they will be compulsory for norms, standards and the very key point, which is rules of origin."

Barnier ended his speech by appealing to the U.K. not to underestimate the huge veto risk on the EU side if its demands are not fulfilled.

While the Brexit withdrawal agreement "is and will be" an EU-only treaty that can be approved by EU governments and the European Parliament, "any agreement on future relations" — be it on trade, defense or aviation — "will be a mixed agreement, requiring the ratification by unanimity not only by the EU institutions but by ... national parliaments" from the 27 remaining EU countries, Barnier said.

"And obviously, even regional parliaments," which would have a veto right, he added. "Nobody can underestimate the risks."