Stephen Booth is the Head of the Britain in the World Project at Policy Exchange.

Border arrangements on the island of Ireland dominated the first phase of Brexit, almost derailing the wider withdrawal negotiations between the UK and the EU altogether. It took the personal interventions of Boris Johnson and Leo Varadkar to break the impasse, unblocking the path to the eventual UK-EU Withdrawal Agreement. Agreeing how to implement the compromises they reached within the Northern Ireland Protocol could yet prove to be just as complex and politically controversial in the next phase of talks.

In recent weeks, UK ministers and EU officials have been increasingly at odds over what the post-Brexit arrangements will mean for goods crossing the Irish sea. The EU insists that a strict implementation of the commitments included in the Protocol necessitates various border checks to be made on goods flowing from Great Britain to Northern Ireland. However, the UK Government has ruled out intrusive checks on trade in either direction and argues that the implementation of procedures envisioned under the Protocol remains subject to discussion and agreement.

To recap, the Protocol, due to come into force at the end of the transition period on 1st January 2021, avoids the need for new North-South border checks on the island of Ireland by creating a special economic status for Northern Ireland. Northern Ireland remains in the UK’s customs territory and will therefore be subject to the UK’s independent trade policy and can be included in any new UK trade agreements. However, Northern Ireland will be subject to the EU’s customs procedures to ensure that goods “at risk” of ending up in the EU single market, rather than being consumed in Northern Ireland, are subject to the correct EU tariffs and regulations. UK authorities are responsible for ensuring procedural compliance, but EU representatives can request to be present at customs or regulatory inspections.

Northern Ireland will effectively remain in the EU’s single market for goods, aligning with EU rules for agricultural and manufactured goods. Finally, the Protocol provides a mechanism whereby, after four years, Stormont can withdraw its consent for the special arrangements, in which case Northern Ireland would revert back to full alignment with the rest of the UK, after a two-year cooling off period.

Confusion flows from the fact that, while the Protocol sets out the provisions of EU law that will apply in Northern Ireland, there is much left unsaid about how these provisions are implemented, supervised and enforced in practice. Exactly how trade across the Irish Sea works will therefore be determined by decisions yet to be taken in a UK-EU Joint Committee, and by the wider UK-EU trade relationship, which is yet to be negotiated. For example, if the UK and the EU achieve their stated ambition of a free trade agreement, some tariff and regulatory issues could be simplified.

Ultimately, the debate is beset by the same conflicting interests witnessed in the previous talks. For the EU, having avoided the prospect of a North-South border for now, the primary concern is the integrity of its external border, which will be shifted to the Northern Ireland border. In the first instance, the EU’s approach to such questions is, as ever, a legalistic one and its base case is that all the usual checks should apply.

On the other hand, the Government not only wants to protect Northern Ireland’s place in the UK internal market. It is also mindful of the potential political instability that could result from any measures that would further alarm Northern Ireland’s Unionist community. It therefore favours pragmatism. Indeed, it is in the New Decade, New Approach paper, which helped restore power-sharing at Stormont, that the Government commits to negotiating “additional flexibilities and sensible practical measures across all aspects of the Protocol that are supported by business groups in Northern Ireland and maximise the free flow of trade.”

Achieving a flexible and light-touch approach to policing the Protocol will require intense diplomatic efforts on the UK’s part over the next ten months. However, the UK can argue that it was the EU which previously suggested that any GB-NI procedures could be “de-dramatised”, with the vast majority of regulatory checks taking place in the marketplace rather than at points of entry. Indeed, Article 6(2) of the Protocol states that the Joint Committee “shall adopt appropriate recommendations with a view to avoiding controls at the ports and airports of Northern Ireland to the extent possible.”

Since the island of Ireland is treated as a single unit for the purposes of animal health and disease prevention, there are already checks on animal imports from Great Britain to Northern Ireland. Reaching a mutual recognition agreement on agricultural standards, similar to that between the EU and New Zealand, could minimise the need for any further checks, though this might also depend on the degree of UK regulatory divergence.

Ultimately, as the EU eventually conceded, the Protocol will only work over the long-term if there is broad-based political consent for it in Northern Ireland. Gaining this consent is going to be a difficult challenge, given the circumstances from which we have started this process. It will certainly require more political sensitivity and less legal rigidity from the EU than we have seen up to now. The Government has wisely committed to ensuring that the Northern Ireland Executive is represented at the UK-EU Joint Committee, which will also be attended by representatives from the Irish government. However, the UK must also convince the EU, and the Republic of Ireland in particular, that this is a shared political challenge and there is a joint interest in establishing workable, pragmatic solutions.