What treaties or (written) agreements would a hard border in Ireland breach, post-Brexit?

Question

Would the hard border that would come up in a "no deal" Brexit (between the Republic of Ireland and Northern Ireland) be violating any binding agreements that the UK has signed? (And the same goes for question for the Republic of Ireland and/or the EU.) Or is it merely politically "unacceptable"?

There's video by the European Parliament which mentioned the Good Friday agreements and some EP resolution. But how binding are these with respect to actually mandating a non-hard border? And what do they actually prohibit or demand with respect to the border?

Answer 1

binding agreements that the UK has signed ... what do they actually prohibit or demand with respect to the border?

The Agreement

The Good Friday Agreement / Belfast Agreement / British-Irish Agreement of 1998 can be downloaded from either the Irish government website or the UK government website. It is titled "The Agreement"

It has two parts:

• a multi-party agreement between political parties of Northern Ireland and
• an international agreement between "the Government of the United Kingdom of Great Britain and Northern Ireland and "the Government of Ireland"

The UK obviously is a signatory to the second part, not the first. However the second part commits its signatories "to support, and where appropriate implement, the provisions of the Multi-Party Agreement"

Borders

This agreement discusses cross-border cooperation extensively but there is no explicit mention of border arrangements that I can find.

Much of the wording is open to interpretation and I would assume that the British-Irish Council would be the body that makes these interpretations.

For example, here is a section on security:

SECURITY
1. The participants note that the development of a peaceful environment on the basis of this agreement can and should mean a normalisation of security arrangements and practices.
2. The British Government will make progress towards the objective of as early a return as possible to normal security arrangements in Northern Ireland, consistent with the level of threat and with a published overall strategy, dealing with:
(i) the reduction of the numbers and role of the Armed Forces deployed in Northern Ireland to levels compatible with a normal peaceful society;
(ii) the removal of security installations;
(iii) the removal of emergency powers in Northern Ireland; and
(iv) other measures appropriate to and compatible with a normal peaceful society.

"normal security arrangements" would presumably include normal security arrangements at the border as well as those elsewhere.

Normal Borders

It can certainly be argued that border-arrangements between countries such as Norway and its EU neighbours are "normal".

If so, the presence of border posts for customs checks is not explicitly prevented by the agreement.

Politico.eu says:

one lesson from Norway is that even with the Nordic country's close ties to the bloc, border checks are necessary. Cars entering Norway at Ørje are stopped and drivers asked for their destination and the purpose of their visit. The border post was recently extended and rebuilt with new barriers and cameras. Staffing has also been increased.

We could also look at borders between, for example, Canada and the USA. Generally in the wider world it is "normal" for border posts to exist and for checks to be made at borders.

Political Declarations

The above is somewhat irrelevant because the Irish government, the British government and the EU have all stated that they have no intention of creating new infrastructure at the border.

These declarations are not treaties or signed agreements but they are a clear indication of current political intent.

UK Example

This government is committed to the Belfast Agreement and to do everything in our power to ensure no return to a hard border between Northern Ireland and Ireland.

ROI Example

In planning for the real possibility of a no deal Brexit, the Government’s approach will continue to be guided by the same priorities:
- ensuring the best possible outcome for trade and the economy
- the protection of the peace process and the Good Friday Agreement, including the principle of consent and there being no Hard Border

Hard border

So far as I know, this term is not defined in any international treaty and so is somewhat vague and ambiguous.

It is likely that people will interpret this differently. In most cases any kind of physical infrastructure at or near the border, perhaps even so little as a traffic camera, is likely to be regarded as constituting a hard border.

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Other commentary

• BBC

  What does the Good Friday Agreement say about a hard border?

  A lot less than you might think. The only place in which it alludes to infrastructure at the border is in the section on security.

  During the Troubles there were heavily fortified army barracks, police stations and watchtowers along the border. They were frequently attacked by Republican paramilitaries.

  Part of the peace deal involved the UK government agreeing to a process of removing those installations in what became known as "demilitarisation".

  The agreement states that "the development of a peaceful environment... can and should mean a normalisation of security arrangements and practices."

  The government committed to "as early a return as possible to normal security arrangements in Northern Ireland, consistent with the level of threat".

  That included "the removal of security installations". That is as far as the text goes.

  There is no explicit commitment to never harden the border, and there is nothing about customs posts or regulatory controls.

  (my emphasis)

None of the above means that any of the parties involved think it would be a good idea to have a hard border - whatever that may mean. So far as I know, all are committed to avoiding it and to supporting the spirit of the agreement and not just the letters of it.

Answer 2

For what it's worth, I'll add this bit, found via FullFact.org; a UK government position paper from Aug 2017 (position which presumably can change with the government):

36. The invisible and open border between Northern Ireland and Ireland is, as the Irish Government has said, arguably “the most tangible symbol of the peace process”. [footnoted to: ‘Ireland and the negotiations on the UK’s withdrawal from the European Union: The Government’s Approach’, May 2017]. Customs controls were first introduced at the land border in 1923, shortly after the establishment of the Irish Free State. These controls, and the associated system of ‘approved roads’, were maintained to varying degrees until the the European Single Market was formally established in December 1992. In 1972 there was a chain of 17 HM Customs and Excise boundary posts at the major road crossing points along the Northern Ireland land border, with the other (over 200) crossings not approved for vehicular traffic. During the ‘Troubles’, customs posts were frequently the subject of bombing attacks. Border crossings and checkpoints were manned by a very substantial military and security presence, including a series of ‘watchtowers’ in border areas, and a number of border roads were blocked by the security forces adding to the disruption created by the approved road network. The Belfast (‘Good Friday’) Agreement included a specific commitment to “the removal of security installations”. [footnoted to: The Belfast (‘Good Friday’) Agreement 10 April 1998.] All military security installations and other infrastructure were removed following the Agreement and the border today is invisible and seamless across its 310 mile/500 km length. As the Irish Government has said, “the disappearance of physical border crossings and checkpoints is both a symbol of, and a dividend from, the success of the peace process”. [again footnoted to the 2017 Irish gov't position.]

So even if its loss is not a breach of any explicit treaty provision, it does seem that at least one of the governments considers the open border "the most tangible symbol" of the GFA peace process.

Answer 3

It is part of Parity of Esteem

I have not been able to find anywhere where the Irish Government asserts that avoidance of a hard border is actually a requirement of the Good Friday/Belfast Agreement but there are statements saying that it is a result of the Agreement:

In respecting the UK decision to leave the EU, we have also consistently held to the view that the final Brexit outcome must include recognition of the unique circumstances of this shared island. With our EU partners, we have worked with the UK to ensure an orderly withdrawal. It has been important to find a deal that works for all sides, for Northern Ireland, for the UK as a whole, for Ireland and for the EU as a whole.

From the beginning, Ireland’s approach has been guided by the principle of securing a deal that worked for Northern Ireland. We have had to find ways to protect the Good Friday Agreement and the gains of the peace process, including avoiding a hard border

Speech of Tánaiste Simon Coveney at the Belfast Chamber of Commerce, 23 October 2019

https://www.gov.ie/en/speech/9666f-speech-for-tanaiste-simon-coveney-td-belfast-chamber-of-commerce/

The position of the UK government appears to be that whether or not the original removal of a hard border was required by the Good Friday/Belfast Agreement, "with communities having grown used to the melting away of the visible border" ensuring that it does not return is now part and parcel of parity of esteem - a key element of the Good Friday/Belfast agreement:

The Government is unshakeable in its commitment to the Belfast (Good Friday) Agreement. The hard-won gains of the peace process have transformed the political and economic life of Northern Ireland since 1998. This commitment to the Belfast (Good Friday) Agreement has therefore framed every aspect of the Government’s approach to Brexit negotiations around Northern Ireland and will continue to do so: recognising its position as a co-signatory of the Agreement, alongside the Irish Government; and its specific responsibilities for governance in Northern Ireland, including its economic well-being (identified in 1998 as a vital pillar of peace) and parity of esteem for all traditions.

...the Government has been committed from the outset to a border without infrastructure or checks – and remains so today. Although the ‘all-island’ dimensions to economic life between Northern Ireland and Ireland remain of smaller scale than its other dimensions (such as external or Great Britain-Northern Ireland trade), the Government understands that it is important to minimise disruption to all island sectors and ensure the free flow of trade and people across the border. Concerns around border infrastructure involved both practical issues and matters of identity, with communities having grown used to the melting away of the visible border due to the improved security situation after 1998. The principle of parity of esteem demanded a particularly sensitive response to this issue.

Northern Ireland Protocol: the way forward, July 2021, CP 502, paras 1 and 3.

Note: by hard border I understand you to mean customs posts on the land border. Obviously there will never be any immigration control as there has been freedom of movement throughout the island for centuries which has nothing to do with membership of the EU.