The Good Friday Agreement and International Treaty Law

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10 April 2023 marks 25 years since the signing of the 1998 Belfast/Good Friday Agreement. The agreement was a remarkable political and diplomatic achievement that has allowed a generation of young people to grow up in a society largely free from the worst kinds of violence that marked the conflict in Northern Ireland.

The 1998 agreement is made up of a political agreement between the UK government, Irish government, and political parties in NI, alongside a bilateral treaty between the UK and the Republic of Ireland. The ‘multi-party agreement’ sets out in detail the agreement reached on NI’s constitutional status; the new NI institutions, including the Northern Ireland Assembly (in ‘Strand One’ of the multi-party agreement); North-South institutions (Strand Two); and East-West/British-Irish institutions (Strand Three). The multi-party agreement also sets out guarantees on ‘Rights, Safeguards and Equality of Opportunity’, and addresses a range of other issues, such as policing. The treaty (the ‘British-Irish Agreement’ or ‘BIA’) was signed the same day the multi-party agreement was concluded, entered into force on 2 December 1999, and was registered with the UN Secretariat on 11 July 2000.

This post will analyse some potential implications of the 1998 agreement’s hybrid nature and subsequent practice under the BIA. In particular, the relationship between the multi-party agreement and the obligations created by the BIA is relevant for future reform of the NI political institutions, and complicates the 1998 agreement’s role in interpretation of the UK-EU Withdrawal Agreement.

The international obligations created by the BIA

The BIA has only four articles. Article 1 contains commitments by the two governments on constitutional issues. The most significant provision for the questions analysed in this post is Article 2:

The two Governments affirm their solemn commitment to support, and where appropriate implement, the provisions of the Multi-Party Agreement. In particular there shall be established in accordance with the provisions of the Multi-Party Agreement immediately on the entry into force of this Agreement, the following institutions:

  • a North/South Ministerial Council;
  • the implementation bodies referred to in paragraph 9 (ii) of the section entitled ‘Strand Two’ of the Multi-Party Agreement;
  • a British-Irish Council;
  • a British-Irish Intergovernmental Conference.

As Christine Bell has observed, the use of hybrid forms – combining non-legal instruments with international treaties and/or domestic legislation – is common when constructing peace agreements, which often need to create commitments for a range of international and domestic, state and non-state actors. Yet this hybrid nature also complicates interpretation of those agreements. Article 2 creates two distinct legal obligations for the parties under international law: a general obligation to support, and where appropriate implement, the provisions of the multi-party agreement; and an obligation to establish, in accordance with the provisions of the multi-party agreement, certain Strand Two and Strand Three institutions. However, although the fundamental principles underpinning the agreement – such as consent and commitment to democratic and peaceful means – remain unchanged, over the past 25 years there have been multiple adjustments to the institutions under all three Strands which have departed from the 1998 text of the multi-party agreement. Two questions therefore arise: 1) whether Article 2 obliges the two governments to implement the multi-party agreement as it was drafted in 1998 or as modified by political agreements after 1998; and 2) how are those politically-agreed changes to the multi-party agreement reflected in the content of these Article 2 BIA obligations?

Although the BIA was concluded after the Vienna Convention on the Law of Treaties entered into force generally and for the UK, Ireland only acceded to the VCLT on 7 August 2006. The BIA therefore does not fall within the scope of the VCLT and is instead subject to the customary international law of treaties. Turning to subsequent agreements and practice under the BIA (under the customary rules reflected in Article 31(3)(a)-(b) VCLT), to what extent does the two governments’ practice over the past 25 years reflect an agreed interpretation of the BIA  as requiring modification of Article 2 BIA when there is a departure from the text of the 1998 multi-party agreement?

Subsequent practice under the BIA and change to the 1998 agreement

Since its signature in April 1998 more than a dozen bilateral treaties between the UK and Ireland relating to NI issues have been registered with the UN Secretariat, many of which implement, add to, or interpret the BIA. Some of these treaties pre-date the entry into force of the BIA itself: on 8 March 1999 four treaties were concluded by which the two governments sought to implement and elaborate on their Article 2 BIA obligation to establish the Strand Two and Three institutions (see here, here, here and here). Other treaties have provided agreed interpretations of the BIA’s provisions. For example, a 2004 Interpretative Declaration by the Irish and British Governments clarified that a proposed change to the Irish Constitution in relation to citizenship ‘is not a breach of’ the BIA.

More important for present purposes are those subsequent treaties which have modified – permanently or temporarily – the operation of various 1998 institutions, departing from the text of the multi-party agreement which is referred to in Article 2 BIA. For example, a 2002 Exchange of Notes between the two governments modified temporarily the operation of Strand Two and Three institutions to allow them to function despite the suspension of the Assembly and absence of NI Ministers. The exchange of notes stated that the BIA and one of the March 1999 treaties ‘shall be read and have effect in accordance with’ its provisions, effectively reinterpreting the obligations to operate those bodies ‘in accordance with’ the 1998 multi-party agreement created by the earlier treaties.

Also significant is the adoption of what seems to be an amending treaty to reflect changes to all three Strands of the multi-party agreement (notably including a change to how the First and Deputy First Ministers are selected) agreed following talks between the two governments and NI political parties at St Andrews in October 2006. A March 2007 treaty between the two governments appears to have amended the Article 2 BIA obligation to implement the multi-party agreement so as to reflect these changes to the operation of the 1998 institutions. This practice suggests that corresponding modification of Article 2 BIA is required where there is a politically-agreed change to institutions or procedures set out in the multi-party agreement.

Yet the two governments’ practice is inconsistent. When political agreement was reached on reforms to Strand One institutions in the 2014 Stormont House Agreement (notably a reduction in Assembly members to 90 from 108 specified in the multi-party agreement), this was implemented through domestic UK legislation, without conclusion of a bilateral treaty. This may suggest that treaty action is required for changes to the operation of the cross-border Strand Two and Three institutions that depart from the 1998 multi-party agreement and its implementing treaties, but that politically-agreed modifications of the multi-party agreement as it relates to the Strand One (domestic NI) institutions are automatically reflected in the content of the first obligation created by Article 2 BIA.

The generally good relations between the two governments on issues related to the NI peace process mean that the possibility of these international obligations being litigated, even after Brexit, seems remote. In implementing the 1998 agreement the focus has rightly been on supporting the political accommodation between actors in NI, and to the extent legal issues arose around the 1998 agreement they focused rather on the domestic implementing legislation. However, recent trends in Assembly election results have reinvigorated debate around whether aspects of the operation of the Strand One institutions as set out in the 1998 multi-party agreement require further revision. The question of how changes to the multi-party agreement can be made, and whether they would require amendment or reinterpretation of the BIA (in addition to the necessary political agreement and domestic legislation), is therefore more than purely academic. Further research is needed to determine what agreed interpretation of the BIA, if any, is established by the subsequent practice of its parties.

The 1998 agreement and the EU-UK Withdrawal Agreement

Although international litigation between the UK and Ireland seems unlikely, in June 2022 the EU launched infringement proceedings against the UK for failure to comply with the EU-UK Withdrawal Agreement’s Protocol on Ireland/Northern Ireland. While it remains to be seen if improved UK-EU relations will see a formal end to the proceedings – the February 2023 Windsor Political Declaration by the EU Commission and UK government provides that ‘These arrangements, when implemented, mean that there will no longer be grounds for the existing Commission legal proceedings against the United Kingdom relating to the Protocol on Ireland / Northern Ireland’ (emphasis added) – in principle the process could end in arbitration.

Although not a ‘rule of international law applicable in the relations between the parties’ to the Withdrawal Agreement (the UK and the EU), the 1998 agreement is relevant to the interpretation of the Withdrawal Agreement, at least when considering the ‘object and purpose’ of the Protocol. The preamble to the Protocol, as well as its ‘Objectives’ in Article 1, make numerous references to the 1998 agreement. For example, the preamble affirms

that the Good Friday or Belfast Agreement of 10 April 1998 between the Government of the United Kingdom, the Government of Ireland and the other participants in the multi-party negotiations, which is annexed to the British-Irish Agreement of the same date, including its subsequent implementation agreements and arrangements, should be protected in all its parts.

The 1998 agreement’s hybrid nature and subsequent practice clearly complicate the interpretative process. At first glance, it appears that only the multi-party political agreement needs to be ‘protected in all its parts’, not the BIA itself. Yet, as the reference to ‘subsequent implementation agreements and arrangements’ perhaps recognises, what the multi-party political agreement now requires, politically and in terms of the international legal obligations it gives rise to, cannot be understood without taking into account the BIA, nor modifications made over the past 25 years through political agreement and subsequent treaties. Determining what exactly it is that needs to be ‘protected in all its parts’ will therefore be a complex interpretative exercise for a tribunal seeking to apply the Protocol. This is before one even considers how particular provisions of the Protocol should be interpreted so as properly to take account of that object and purpose.

In the debates around Brexit there has been a tendency by some participants to characterise those parts of the 1998 agreement they find useful as somehow immutable, and those they dislike as rather more flexible. Given the changes that have taken place over the last 25 years, it is true that the question is not whether the 1998 agreement can be modified but how this can be achieved and whether the means of modification depend on the kind of change being contemplated. The analysis above has shown that this is a question to which international treaty law must provide at least part of the answer.

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