Daniel Halberstam: EU Brexit Litigation: A Short Guide to the Perplexed

Given Boris Johnson’s explicit vow that he’d rather “be dead in a ditch” than ask Brussels for an extension, and his consiglieri’s statement that the government would “scupper” any extension by refusing to negotiate because the “duty of sincere cooperation will be down the toilet,” one might be forgiven for thinking that the Government’s strategy—despite the occasionally hopeful press release—is to run out the clock on the October 31 deadline or the next one, in the hope that, no matter how, they will have succeeded in taking the U.K. out of the EU.

It may, therefore, be useful to remind No. 10 of the practical legal consequences of some of their actions. To be sure, the law is only a backdrop when the aim is revolution. But if the aim is to work within the law, there are a series of constraints the current government may wish to consider.

Jeff King has taken great care to explain some of the domestic limitations under which the Government currently labours (see here and here). I shall take up the thread here by turning to how EU law ties into the U.K.’s constitutional obligations.


Begin with basics. Article 50 TEU allows a Member State to withdraw “in accordance with its own constitutional requirements.” As the European Court of Justice held in Wightman, Article 50 demands that the withdrawal process be “orderly” and “democratic.” The decision to withdraw, the Court also held, was not finalized by the original notification, but an ongoing intention subject to revision and reconsideration through that state’s “democratic process in accordance with its constitutional requirements.”

Although the Wightman court only addressed a possibly changed intention, I suggest the same must hold true for an unchanged intention, i.e. that the refusal to change one’s intention to withdraw cannot be tainted by manifestly undemocratic and unconstitutional conduct. How else could we be certain that the intention we must respect was still there?

We can, then, in my view, infer from Wightman that not just the initial decision to trigger Article 50, but the Member State’s entire withdrawal process must be democratic and heed that state’s constitutional requirements.

And, here, we’re already in for the first catch among many: for as long as the European Communities Act of 1972 (“ECA 1972”) – which is a constitutional statute – is in force, the U.K.’s constitutional duties include heeding foundational EU law duties, including the duty of sincere cooperation. See Miller v SS for Exiting the EU [2017] UKSC 5 (“Miller I”).

Lest you think of paper tigers, let me count some ways to enforce this.

Member State Courts

Domestic courts may enforce these obligations, of course, as did the Scottish Court of Session earlier this week when it took the remarkable measure of invoking nobile officium to retain jurisdiction and monitor the Government’s implementation of the European Union (Withdrawal) (No.2) Act 2019 (“Benn Act”), which demands that the Government seek an extension if no agreement is reached by October 19.

Domestic courts can and should similarly enforce other constitutional requirements, e.g., ensuring that the Government has not disregarded Parliament’s requirement in the European Union (Withdrawal Act) 2018 (a constitutional statute, I would argue, in light of Miller I) to give “due regard” to the Belfast Agreement and the Northern Ireland Act (another constitutional statute) by triggering the repeal of the ECA 1972 in the absence of any withdrawal agreement.

And, not least because following EU law is also a U.K. constitutional requirement for as long as the ECA 1972 is in force, domestic courts can and should also enforce the Government’s duty of sincere cooperation – say, if the Government were to return to its position of categorical refusal to negotiate in the hope of running out whatever the next exit clock may be.


The Court of Justice could become involved in a host of ways. Let me mention just a few of the more salient ones.

First, Member State courts hearing claims concerning an unconstitutional exit, could (and under Article 267 TFEU, under certain circumstances, must) send a reference to the CJEU on the consequences under EU law from such action.

Second, the Commission could sue the U.K. before the CJEU directly under Article 258 for failure to fulfill its Treaty obligations.

Whichever way these claims come to Luxembourg, the CJEU could, if necessary, as others already pointed out [e.g. Pavlos Eleftheriadis], immediately toll any upcoming Brexit deadline by interim measure under Article 279 TFEU until the matter was properly heard. Moreover, in its final judgment, the CJEU could pronounce the withdrawal period tolled until any manifest domestic constitutional violation was cured. Indeed, the CJEU may even hold that the unconstitutional action at some point has undermined exit to such an extent as to require the U.K. to start its withdrawal process all over again!

And that’s just playing nice. For those who think the U.K. is out after this or the next Brexit deadline passes no matter what EU law says, there could be even greater surprises down the line.

One would be a lawsuit by the Commission, again under Article 258 TFEU, or another Member State under Article 259 TFEU, against the purportedly “former” Member State that wasn’t. One way or another, the CJEU could hold the U.K. had not, according to EU law, left the EU, and order the U.K. to comply with the Treaty or face fines. Fanciful, to be sure, in terms of actually keeping the U.K. in the Union. But those fines would be added to the U.K.’s divorce bill, raising the baseline for negotiations of what the U.K. would have to pay to really get out.

Lastly, there’s the nuclear option. Either by suit against the EU Council under Article 263 TFEU or by simple referral (say from a Member State or the European Parliament) under Article 218(11) TFEU, the CJEU could examine the Council’s decision to begin negotiations for an association agreement with the purportedly “former” Member State, i.e. the state that thinks it left. The CJEU could hold that, for these purposes as well, there had been no legal exit from the Union due to manifest failure to heed the Member State’s constitutional requirements. Regardless of whether any U.K. official at that point thinks the duty of cooperation was “down the toilet,” under EU law such a ruling would bar all EU institutions from negotiating an association agreement with the U.K. After all, association agreements cannot be made between the EU and a current Member State.

This last option, i.e., declaring the U.K. never left and hence cannot become partner to an association agreement, would not need to come before the Brexit deadline. Indeed, there’s no rush at all. It could be initiated just before, or sometime after, the Council opened negotiations on a future association agreement with the Member State that thinks it left but never did.

A final Twist – or “Catch-22”

If the CJEU were to hold that an association agreement with the U.K. were impossible because of a disorderly, undemocratic, and unconstitutional withdrawal process, only a Treaty amendment pursuant to Article 48 TEU could legally lift that bar. Under Article 48, however, such an amendment would require unanimity in the Council, the European Parliament’s consent, and ratification in all the Member States. And this, in turn, could require ratification by the U.K. as Member State of the EU— even if the U.K.’s voting rights in the EU Council had been suspended under Article 7 TEU for a persistent breach of the rule of law.

Daniel Halberstam, Eric Stein Collegiate Professor of Law, Associate Dean for Faculty & Research, and Director of European Legal Studies at the University of Michigan Law School

(Suggested citation: D. Halberstam, ‘EU Brexit Litigation: A Short Guide to the Perplexed’, U.K. Const. L. Blog (11th Oct. 2019) (available at https://ukconstitutionallaw.org/))