The 1969 treaty that could help the UK slip a Brexit trap

LONDON — Britain could walk away from the Irish backstop — but not easily.

With little evidence that MPs are coming round to supporting Theresa May’s Brexit deal, ministers are becoming increasingly desperate to find a way to reassure their backbench colleagues before the crunch vote next week.

According to a report in the Sunday Times, some in government are now turning to a decades-old international treaty that they hope could persuade some of their colleagues to swing behind the deal. They say it provides an escape route from the Brexit deal May has agreed with Brussels should the EU ever seek to keep Britain permanently locked in a customs union with the EU. Unfortunately for them, it’s not that simple.

On January 9, MPs began five days of debate on May’s Brexit deal, culminating in a vote to ratify it (or not) Tuesday evening. But the contentious Northern Ireland backstop — an arrangement to avoid a hard border with the Republic of Ireland — remains highly controversial with Brexiteers and the Democratic Unionist Party, whose MPs give the prime minister a majority in parliament. They claim the backstop represents a threat to the integrity of the U.K.

In the absence of legal guarantees from the EU that it will not trap Britain in the backstop permanently — which EU27 leaders say they won’t provide because it would amount to a renegotiation of the text — some ministers are speculating about a simpler alternative if the EU tries to keep the U.K. in the backstop. They argue that the U.K. could invoke the 1969 Vienna Convention on the Law of Treaties to unilaterally pull out of the deal.

This would effectively mean tearing up a global agreement and walking away, but advocates of this potential course of action say there is international legal protection for doing so set out in the Vienna Convention, a body of law that sets out the rules that govern treaties. All Britain has to do is notify the EU of its intention to leave and 12 months later, kabam! — no Withdrawal Agreement and so no backstop.

The problem is the Vienna Convention does no such thing.

In fact, according to international law experts, the Vienna Convention sets out in stark terms that a treaty cannot be abandoned if there is no provision within it to do so.

The U.N. Charter, for instance, has no express provision to withdraw.

Article 56 of the Vienna Convention states that “a treaty which contains no provision regarding its termination and which does not provide for denunciation or withdrawal is not subject to denunciation or withdrawal.”

There are only two ways out of this. One, if the treaty “intended” to have an exit mechanism. Or, two, if an exit mechanism was “implied” within the treaty.

Neither exist in the U.K.’s exit treaty, say international lawyers.

What’s worse for Brexiteers, the Withdrawal Agreement’s contentious Irish backstop clause not only does not have a provision to leave but explicitly sets out that it cannot be left — a double lock tying all future U.K. governments to May’s deal.

According to the Withdrawal Agreement, the backstop provisions “shall apply unless and until they are superseded, in whole or in part, by a subsequent agreement.” So until London and Brussels agree their ultimate trade deal, the backstop continues to apply.

This means that whatever is said over the coming days, the U.K. is not only binding itself into a treaty with no exit provision, but would be actively breaking international law if it decided to walk away from the treaty simply because it no longer liked the obligations, should MPs vote to ratify it on January 15.

So the backstop is a lock without a key. But that doesn’t mean it cannot be picked.

Despite the bind provided by the “unless and until” clause, leading international law experts believe there are ways the U.K. can free itself from the backstop should it ever threaten to become permanent.

This is because, while the backstop has no exit clause — it creates obligations on the EU to find a permanent arrangement to replace it.

This is the U.K.’s legal and — more importantly — political leverage, according to the international law experts and ministers who spoke to POLITICO.

Article 60 of the Vienna Convention guarantees the right of a party to walk away from a treaty if the other side has not kept up its side of the bargain. It states: “A material breach of a bilateral treaty by one of the parties entitles the other to invoke the breach as a ground for terminating the treaty or suspending its operation in whole or in part.”

In a research paper for the think tank Policy Exchange, Guglielmo Verdirame, Stephen Laws and Richard Ekins point out that the backstop is explicitly “intended to apply only temporarily.” Furthermore, the treaty obligates both sides to use “best endeavours” to conclude a successor treaty by December 31, 2020.

Should the U.K. come to the conclusion that the EU was keeping it locked in a backstop unreasonably, it could claim a material breach of the Withdrawal Agreement and withdraw from parts or all of the deal.

Henry Newman, director of the think tank Open Europe, said the U.K. should try to negotiate a side agreement with the EU giving it a safety cord to pull should it ever feel the EU had not kept up its side of the bargain. This would say that the U.K. government believes it reserves the right to withdraw from the backstop should the EU be in “material breach” of its obligations.

One government minister loyal to May said this should take the form of an “interpretive legal document.”

Newman said: “What No. 10 needs to agree with the EU is a legally binding side agreement that clarified that if negotiations did not proceed in good faith, the U.K. would reserve its rights to repeal the Withdrawal Agreement under the Vienna Convention.”

“That would give critics of the deal some comfort that the U.K. would be able to pull a ripcord if it became ‘stuck’ in the backstop. The Commission already knows the backstop could not survive indefinitely — as they put it, it’s rain-proof but not tsunami-proof.”

Steve Peers, professor of EU, human rights and world trade law at the University of Essex, said the Withdrawal Agreement created arbitration mechanisms that would kick in should one side accuse the other of failing to adhere to the terms of the deal.

However, Peers said that under international law — governed by the Vienna Convention — the U.K. could “refuse to be bound by a treaty in practice” and its courts could give effect to that domestically.

This would probably mean repealing or amending acts of parliament that brought the Withdrawal Agreement into U.K. law. In the U.K. “international treaties only have legal effect within U.K. domestic law to the extent that [domestic] law gives effect to them,” he said.

The EU would be free to apply sanctions to the U.K. — perhaps by increasing tariffs to WTO levels — but, ultimately, could not stop Britain leaving.

This article is from POLITICO Pro: POLITICO’s premium policy service. To discover why thousands of professionals rely on Pro every day, email [email protected] for a complimentary trial.

Click Here: Spain Football Shop