Professor Richard Ekins is Head of Policy Exchange’s Judicial Power Project. He is a Fellow of St John’s College and an Associate Professor in the University of Oxford.

Geoffrey Cox’s advice on the UK’s legal position in relation to the backstop was received and debated on an extraordinarily compressed timetable.  The relevance of the Good Friday Agreement (GFA) only really came up in the Commons minutes before the meaningful vote on Tuesday evening.  In consequence, a number of important points have been overlooked or misunderstood by some MPs and commentators.

In a new paper published yesterday by Policy Exchange, Professor Guglielmo Verdirame, Sir Stephen Laws and I take a second look at the Withdrawal Agreement, Protocol, Joint Instrument, Unilateral Declaration, and Attorney General’s advice, and explain why the legal risk of being trapped in the backstop is much lower than many assume.

The “good faith” obligation in the Withdrawal Agreement has a particular meaning in international law, which has been overlooked, and is not equivalent to the absence of dishonesty, malice, or bad faith in domestic law.  It would be possible for the UK to establish that the EU was in breach of that obligation if it persistently and unreasonably refused to conclude an agreement that replaced the backstop.  The suggestion made by some that the “good faith” obligation would end up being authoritatively interpreted and applied by the Court of Justice of the EU is mistaken – this is an obligation in international law concerning negotiations about a new agreement.

The “good faith” obligation is reinforced by the “best endeavours” obligation in the Protocol, which sharply minimises the risks that negotiations will become intractable or that the backstop will become permanent by default.  This “best endeavours” obligation has teeth and is more robust and specific than other equivalents in international law which have been taken seriously and been significant.

The Joint Instrument and Unilateral Declaration reinforce and specify these obligations of “good faith” and “best endeavours”.  This sharply reduces the risk that the EU will attempt to make the backstop permanent by default in order to secure an advantage in negotiations about its replacement, which was a real risk in view of some of the comments attributed to key EU figures, including Emmanuel Macron and Sabine Weyand.

The Joint Instrument makes clear that the EU cannot insist that the backstop be replaced by an agreement that replicates the backstop – if there are other ways to secure the objectives of the Protocol, which includes especially the protection of the GFA, these cannot be unreasonably rejected.  It would be strong evidence of a breach of the “good faith” obligation if the EU were to attempt to insist on objectives that could not be squared with the GFA or to withhold agreement when the UK had proposed reasonable alternative means to protect the GFA and avoid a hard border.

Many people have overlooked the priority that the GFA has within the Protocol, a priority confirmed and stressed by the Joint Instrument and the Unilateral Declaration.  If the backstop were to become permanent by default then the UK, Ireland and the EU would all be at legal risk.  This incompatibility between a “permanent by default” backstop and the GFA might become clear by way of a court ruling that the backstop’s permanence violated the rights of people in Northern Ireland under Article 3 of Protocol 1 of the ECHR (the right to free elections).

There is precedent here in relation to Gibraltar’s lack of representation in the European Parliament.  That the backstop had become permanent de facto and its perceived incompatibility with the GFA and its principle of consent might also be made clear by the Stormont Assembly itself.  This incompatibility would constitute a fundamental internal contradiction within the Protocol and this would be an arguable reason to bring the backstop to an end on the grounds that it constituted a fundamental change of circumstances.  Lord Pannick has reached a somewhat similar conclusion.  In the first instance, it would make the obligation to negotiate and to conclude an agreement ever more forceful and urgent.

The final paragraph of Cox’s advice is best understood to confirm only that a theoretical risk remains, one that is highly unlikely to arise in practice because of the stringent obligations to which the UK and EU are both subject to avoid intractable differences precluding agreement.  It is difficult to see how differences between the EU and the UK could become “intractable” when EU and UK conduct is subject to the arbitration process and is capable of being resolved in that way.

However, if it truly were the case that agreement was impossible, that the objectives of the Protocol could not be satisfied by any compromise, then this would also arguably constitute a fundamental change of circumstance.  The possibility of compromise and agreement is, quite rightly, a foundation of the Agreement and Protocol and the parties do not anticipate that they will be unable to reach agreement.  Again, well before one reaches that conclusion, or that impasse, which is what it would be, the reasonableness of EU and UK conduct could be challenged in arbitration.

In other words, it was a mistake to read the final paragraph of the Attorney’s advice to establish that the UK could, and perhaps even would, end up trapped in the backstop.  Such an assessment was premature and should be rethought.