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The past 72 hours perfectly illustrate how the prime minister has exhausted various options to get her withdrawal agreement through. The government has changed tack twice this week, resorting to legal argument rather than political strategy as a way to entice the ERG, Brexiteer wing and DUP colleagues to support her deal. As a result, the outcome of the third vote next week relies heavily on a firm legal basis, with the two groups crucial for a government win relying on legal opinions to dictate their political decisions.

Against the backdrop of the votes this week, there has been an ongoing conversation around the use of Article 62 of the Vienna Convention to remove the UK and Northern Ireland from the backstop as agreed in the withdrawal agreement. This has been one of the key fears for both the ERG and DUP, who have expressed concerns about being tied to the EU indefinitely through the backstop mechanism in lieu of a new trade relationship.

What is Article 62?

The Vienna Convention on the Law of Treaties, adopted in 1969, is an international treaty that entered into force in 1980. The convention has been referred to as the ‘treaty on treaties’ and was drafted by the International Law Commission of the United Nations. It governs international treaty law through the 85 Articles ratified by over 110 states. The convention is very much seen as a last resort for countries, and as a result there is very little legal precedent in existence.

Article 62 of the Vienna Convention states that a party can terminate or withdraw from a treaty in exceptional circumstances if there is ‘a fundamental change of circumstances’ since the treaty’s agreement which ‘was not foreseen by the parties’.

Does it affect the withdrawal agreement?

In legal advice provided to the ERG and DUP last night, attorney general Geoffrey Cox suggested that Britain will be able to pull out of the Irish backstop if it has a ‘socially destabilising effect on Northern Ireland’ – thought to constitute the ‘fundamental change of circumstances’ referenced within the article. Although his advice is not yet fully published, he is reported to have said: “It is in my view clear and undoubted in those exceptional circumstances that international law provides the [UK] with the right to terminate the withdrawal agreement.”

Fundamentally, he is suggesting that social or political instability in Ireland would provide the UK with a unilateral right to exit the backstop. If his position is adopted by the ERG and DUP, it would put May’s deal on a much firmer footing going into the vote next week.

Mere days ago, Cox gained accolades, particularly from the legal profession, for his refusal to bow to pressure by Theresa May on his legal guidance about the joint instrument resulting from May’s last minute flit to Strasbourg on Sunday. However his opinion on Article 62 has been shunned as ‘badly misconceived’ by the ‘star chamber’ of Brexiteer lawyers assembled by the ERG and DUP. Twitter is abound with international legal experts denouncing his opinion, with a couple of factors most noted:

Firstly, precedent indicates that the legal threshold required to prove ‘a fundamental change of circumstances’ under Article 62 is exceptionally high. Both the fall of the Berlin Wall and the split of Czechoslovakia were not considered sufficiently exceptional for the use of the article in previous cases.

Secondly, within the article’s wording there lies an explicit understanding that this change in circumstance could not have been “foreseen” at the time of a treaty’s signing. The very discussion around the use of the article, and legal implications of the backstop itself – which only comes into play if a solution cannot be found – indicate that any change of circumstances are arguably foreseen.

Finally, questions have been asked about the political implications of invoking Article 62, which some argue would demonstrate significant bad faith by the UK, and could negatively impact the UK’s standing when it comes to trade and treaty negotiations for decades to come.

In short, while Article 62 may be a legally viable instrument that does in fact allow a country to exit a treaty, it is by no means certain that the International Court of Justice would rule that any social or political change in Northern Ireland would allow the UK to exit the backstop under international law. Article 62 may be yet another dead end for May and is not the unicorn solution that many have been searching for, and May’s effort to win support continues.

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