I. Immigration Arrangements

Having long operated without much debate, Brexit forced the CTA to the forefront of the UK’s political discourse. Brexit’s leading proponents acclaimed the CTA arrangements with David Davis, as Brexit Secretary, dismissing concerns that the UK–Ireland land border would become more difficult to traverse after Brexit with the assertion that “there was an open border before either of us was a member of the European Union, and we had the common travel area before we were members of the European Union.”Footnote ⁸ But little effort was made to define the CTA or explain how it functioned in practice in the months before the Brexit referendum.Footnote ⁹ Prior to Brexit, there was no urgency to determine the CTA’s precise content, its legal status, or the extent to which it relied upon EU law.Footnote ¹⁰ Arrangements upon which people moving between these jurisdictions base their daytoday lives remained opaque.

If the border in Ireland is one part of “the great wave of border creations after the First World War,”Footnote ¹¹ the CTA followed as an attempt at mitigation. It was conceived in 1922 as an informal arrangement that relieved both the UK and Irish Free State of the troublesome task of immigration enforcement on the new border. Although restrictions were introduced in the early months of the Second World War, and would last for more than a decade, the CTA would be reinstated in its modern form in 1952. One of the most extraordinary aspects of these arrangements is that they have operated since then, despite being based upon “no international treaty of any kind.”Footnote ¹² Both the UK and Ireland have, at different times, emphasized that the CTA arrangements are not a function of binding international law but a policy maintained on the basis of mutual national self-interest. In the 1950s, Irish policy makers were adamant that the CTA did not formally bind Ireland’s ability to set its own immigration policy, underscoring Ireland’s status as fully independent from the UK.^{Footnote 13} Various UK Governments, moreover, have used the CTA’s non-binding nature to adjust the rights of Irish citizens resident in the UK, and even to unilaterally review the CTA’s operation in 2008.Footnote ¹⁴

In practice, the CTA’s significance for Ireland has often resulted in the Irish Government swiftly acting to align with new UK immigration policies.Footnote ¹⁵ The introduction of the much-criticized “direct provision” arrangements for asylum seekers in Ireland, for example, was explicitly justified on the basis that if Ireland operated a less restrictive policy towards asylum seekers than the UK, they would be enticed to move through the UK to Ireland using the CTA.Footnote ¹⁶ Ireland’s courts, moreover, have upheld the refusal of a visa on the basis that an individual is seeking to use Ireland purely as a means to access the UK, thereby circumventing UK checks.^{Footnote 17} Ireland thus makes visible efforts to maintain the CTA’s external face,^{Footnote 18} which generally imposes visa requirements upon non-EU/EEA/Swiss foreign nationals traveling between the CTA’s constituent parts.^{Footnote 19} The lists of third countries whose citizens are required by Ireland and the UK to obtain entry visas are largely aligned,Footnote ²⁰ and the two countries share data on visa acceptances and refusals.Footnote ²¹

The UK Immigration Act 1971 provided what were, for some time, the only significant references to the CTA in UK law.Footnote ²² The Act specified that travel into the UK from the Channel Islands, Isle of Man, and the Republic of Ireland “shall not be subject to control under this Act,”^{Footnote 23} making exceptions for third-country citizens.Footnote ²⁴ In other words, the UK permitted entry of individuals from other parts of the CTA without border checks.Footnote ²⁵ Ireland long maintained equivalent arrangements but from the 1990s introduced passport checks on air travelers, on the basis that this documentation was required for an individual to demonstrate their CTA travel entitlement.Footnote ²⁶ And despite the limited monitoring of cross-border travel for immigration purposes, citizens of third countries crossing the CTA’s internal borders are legally required to possess any necessary permissions for entry. These lasting arrangements illustrate the continuing significance of immigration rules within the CTA framework. Ireland and the UK’s special arrangements for each other’s citizens, nevertheless, extend far beyond creating a free-movement zone.

II. Reciprocal Rights and Obligations

The UK Government has repeatedly emphasized its ongoing commitment to the CTA after the 2016 Brexit referendum, identifying a range of reciprocal rights and entitlements for Irish citizens in the UK—and UK citizens in Ireland—as being derived from the CTA. These include the right to work without permit, the right to access education, the right to vote in local and parliamentary elections, and the ability to access social welfare entitlements and benefits, health services, and social housing.^{Footnote 27} But the fact that the CTA was not grounded in any comprehensive legal document called into question how this catalog was assembled.Footnote ²⁸ By September 2017, the UK Government and EU Commission’s Brexit negotiators had mapped some 142 aspects of cross-border cooperation in Ireland and acknowledged that, of these, ninety-six were facilitated by EU law and twenty-four were facilitated by the CTA.Footnote ²⁹ Even if the details of this mapping exercise were not made public until June 2019, the UK Government was increasingly conflating the free-movement zone with distinct issues relating to the rights and obligations of people using this zone.Footnote ³⁰

Ireland and the UK treat each other’s citizens differently from other foreign nationals in their domestic law. In Ireland, individuals who are not Irish citizens are categorized in law as “non-nationals.”^{Footnote 31} Over the decades, various statutory instruments have separated out UK citizens from this status.^{Footnote 32} In the UK, the Ireland Act 1949 establishes a presumption that Ireland—and its citizens—are not to be treated as “foreign” for domestic law purposes.^{Footnote 33} But this language is dated and open to interpretation. When modern UK immigration law is framed in terms of UK citizens and non-UK citizens, any rights supposedly provided by a status of “not foreign” are inherently ambiguous.Footnote ³⁴ Both countries’ laws regarding immigration status are supported by other provisions that, while not mentioning the CTA, support broad equivalence of treatment between people from its constituent parts and home citizens. For example, both Ireland and the UK’s electoral law makes explicit provision for voting rights for each other’s citizens in parliamentary elections.^{Footnote 35} In light of the informality of the CTA arrangements, such “reciprocity” is rarely exact; in considering the impact of Ireland and the UK’s opt-out from Schengen on the application of EU law, the UK Supreme Court affirmed that “it would be going too far to insist on a precise match between the arrangements on one side of the Irish Sea and the other.”Footnote ³⁶

Neither the UK nor Ireland guarantees that the other’s citizens will continue, indefinitely, to be treated in a manner that is in most respects equivalent to its own citizens. Instead, both effectively maintain a separate category in nationality and immigration law for the other’s citizens. This category is conditioned by an understanding that each state will treat the other’s citizens as roughly equivalent to home citizens. The UK Government’s catalog of reciprocal rights therefore follows from the Ireland Act 1949’s recognition that Irish citizens are not foreign. Specific manifestations of this principle are, however, scattered across disparate areas of domestic law and policy. For instance, conditions for accessing public healthcare once a resident is in the other jurisdiction are found within domestic healthcare law, whereas admissions policies for publicly-funded primary and secondary education are found in domestic education law.Footnote ³⁷ In practice, these rights subsist only so long as the UK and Ireland’s legislatures maintain them.

III. UK-Ireland Arrangements and EU Law

Brexit has therefore exposed significant shortcomings inherent in the CTA’s historical informality. Most of what the UK Government calls CTA “rights” rest on no firmer legal basis than dated language in aging domestic legislation. At a more fundamental level, upon Brexit the land border between the UK and Ireland will become a frontier of the EU. The continuation of the CTA after Brexit therefore required negotiations and compromises between the UK, Ireland, and the EU. For the UK, individuals who are not citizens of the CTA members could take advantage of the absence of passport or visa checks at this land border. The resultant “backdoor” is difficult to square with the Brexit narrative of “taking back control” of immigration.Footnote ³⁸ For the EU, by contrast, the exceptions to EU border controls—which it had made for Ireland and the UK when both were Member States to enable them to maintain the CTAFootnote ³⁹—become harder to sustain in the context of Brexit.Footnote ⁴⁰ This EU dimension is significant, for although the CTA predated Ireland‘s EU membership, Ireland will have to fulfill EU law obligations after Brexit which did not affect the operation of the CTA before 1974.Footnote ⁴¹

The CTA’s mutual benefits, alleviating the burden of administering the land border and improving population flows across the Atlantic Islands, have largely sustained versions of the arrangement for a century.Footnote ⁴² It is dependent on trust between the parties and a certain measure of tolerance by the EU. There is, however, no obvious legal recourse if trust breaks down, or slowly erodes, in the context of Brexit. The Police Service of Northern Ireland (PSNI), for example, has complained that shortcomings in Ireland’s immigration enforcement in recent years contributed to a spike in immigration offenses within Northern Ireland.Footnote ⁴³ Westminster responded with more extensive immigration enforcement powers for the PSNI along the land border,Footnote ⁴⁴ but the episode evidences the tensions surrounding border enforcement. Westminster’s EU Committee has thus warned that “both Governments need to take action to convince EU colleagues of its [the CTA’s] necessity, in particular in the context of the unique circumstances in Northern Ireland.”Footnote ⁴⁵ As we will discuss below, protecting the CTA became an area of commonality between the UK and Ireland in the Withdrawal Agreement negotiations.Footnote ⁴⁶

Notwithstanding the EU’s ultimate consent to the CTA continuing, Brexit continues to pose challenges, in particular because of the degree to which EU law currently supports CTA arrangements that could otherwise be abridged by domestic law and policy. When the CTA was instituted, state welfare provision was limited and Irish and UK citizens continued to share the overarching status of British subjects.Footnote ⁴⁷ There was, therefore, no need for legalized arrangements for reciprocal access to welfare provisions until the late 1940s, when welfare provision expanded, Ireland left the Commonwealth, and the UK reformed its nationality law.Footnote ⁴⁸ Legislation in both countries at this critical juncture affirmed reciprocal treatment of each other’s citizens, but these measures were not couched in terms of legal protections against discriminatory treatment on the basis of nationality. In Ireland, the relevant statutory instrument contained a particularly vague assurance that UK citizens “enjoy in Ireland similar rights and privileges to those enjoyed by Irish citizens in the United Kingdom and Colonies.”Footnote ⁴⁹

The UK’s Ireland Act 1949, moreover, has not played a prominent part in the litigation initiated to protect the legal interests of Irish citizens resident in the UK. In the rare cases in which it has been invoked, such as Re O’Conor’s Application,Footnote ⁵⁰ it has not had a meaningful impact. In this case, Mr Justice Girvan responded to claims that, under the terms of the 1949 legislation, Irish citizens are not foreign, by emphasizing that “neither are they British citizens.”Footnote ⁵¹ Instead they fell into an intermediate category, in which it was up to the courts to determine whether differentiated treatment was acceptable. As a result, the rights which have come to be associated with the CTA can sometimes be threatened by proposals which take little account of its operation. For example, the Goldsmith Report into UK citizenship, commissioned by Gordon Brown’s Labour Government, advocated removing Irish citizens from the UK parliamentary franchise in order to bolster the connection between UK citizens and Westminster.^{Footnote 52} Although the proposals came to nothing, they illustrate how the CTA can be overlooked within UK policy making.

Only after Ireland and the UK joined the European Economic Community (EEC) in 1974 did Irish citizens in the UK and UK citizens in Ireland gain an effective framework through which to mount legal challenges against applications of domestic law that discriminated against them as foreign nationals. Free movement rights proved harder to circumvent than the CTA’s vagaries. In 1974, following the Birmingham and Guilford bombings by the Provisional Irish Republican Army, UK Prime Minister Harold Wilson ordered contingency planning for travel restrictions on Irish citizens travelling into Great Britain. Officials agonized that such controls would cause “resentment,” and could therefore exacerbate the threat of terrorist attacks in Great Britain.Footnote ⁵³ They also identified a vital legal impediment; while any affected European Convention on Human Rights obligations could be subject to derogation,Footnote ⁵⁴ there was no such means to prevent an EEC Commission enforcement action against the UK “on the grounds that it was failing to meet its obligations under the [EEC] Treaty.”Footnote ⁵⁵

The use of European law in litigation began to influence the CTA’s workings. In Singh,Footnote ⁵⁶ the European Court of Justice (ECJ) recognized that UK nationals could—by setting up residence in another Member State, including Ireland—activate their EU law rights and circumvent UK restrictions on the residency of spouses who are third country nationals. The development of EU citizenship after the Maastricht Treaty reinforced this trend.Footnote ⁵⁷ In Zhu and Chen,Footnote ⁵⁸ the CTA offered little protection for a Chinese citizen and her child, who had Irish citizenship by virtue of her birth in Belfast, against UK Home Office officials’ refusal to grant them residence permits. The ECJ, however, decided that the child—for as long as she had sickness insurance and was not a burden on the public finances of the UK as host State—enjoyed “a right to reside for an indefinite period in that State.”Footnote ⁵⁹ Furthermore, these EU law rules also “allow a parent who is that minor’s primary carer to reside with the child in the host Member State.”Footnote ⁶⁰ A decade later, in McCarthy,Footnote ⁶¹ the Court confirmed that the UK and Ireland’s opt-out from the Schengen free movement area “does not permit the United Kingdom to determine the conditions for entry of persons who have a right of entry under EU law.”Footnote ⁶² These cases contributed to a narrative in the UK that the ECJ was enabling individuals to abuse the rights available to them under EU law.Footnote ⁶³ Without such judicial oversight, however, freedom of movement would have conferred no meaningful protections upon individuals.

EEC membership also necessitated extensive reforms to protectionist labor market practices, which had persisted—in both the UK and Ireland—despite the CTA.Footnote ⁶⁴ The vestiges of such practices, such as provisions in Northern Ireland’s child benefit law that disadvantaged some cross-border workers into the 1990s, were broken down only through litigation which drew upon European law. In McMenamin,Footnote ⁶⁵ the claimant was not paid the full rate of child benefit, which would ordinarily apply as a result of her employment in Northern Ireland, because she and her children were resident in Ireland. The ECJ ruled that in these circumstances, the UK was obliged to top up any payments by Ireland to ensure that the claimant received a level of child benefit equivalent to that of her colleagues resident in Northern Ireland.Footnote ⁶⁶ Cases like this built up the detailed provisions coordinating social security under EU law.Footnote ⁶⁷ Gráinne McKeever emphasizes the value of this body of EU law in the CTA context, in harmonizing “hugely complex tax systems” and mapping them to “the complexity of individual lives.”Footnote ⁶⁸ More recently, EU rights of access to servicesFootnote ⁶⁹ enabled a parent from Northern Ireland to challenge the decision of HM Revenue & Customs that she had not been entitled to tax credits on the basis that she had used a childcare provider which the scheme did not support because it was based in the Republic of Ireland.Footnote ⁷⁰

The tendrils of EU law therefore stretch deep into the existing cross-border arrangements between the UK and Ireland.Footnote ⁷¹ People circulating between these countries under the CTA rely upon this framework of rules to conduct their lives. Figures recently released to Dáil Éireann reveal that social security coordination on pensions alone covered some 132,000 people living in Ireland in receipt of UK state pensions, and that 28,760 people living in the UK received some state pension contribution from Ireland.Footnote ⁷² Brexit, however, promises to end the UK’s obligations to EU citizens, including Irish citizens, which derive from EU law. UK citizens in Ireland, moreover, will “no longer enjoy the same level of rights and safeguards as currently provided by EU law.”Footnote ⁷³ Without the support of EU law’s binding obligations, the rights and entitlements hitherto extended by Ireland and the UK to each other’s citizens appear increasingly vulnerable to the shifting sands of post-Brexit politics.

IV. The CTA and the People of Northern Ireland

Brexit brings with it a further Northern Ireland-specific complication to the CTA arrangements. Ireland has, since the 1950s, made explicit a statutory provision enabling people born in Northern Ireland to claim Irish citizenship.Footnote ⁷⁴ Following the 2004 citizenship referendum, this right was restricted to children born in Northern Ireland with at least one parent who was an Irish or UK citizen.Footnote ⁷⁵ These changes were, in part, a response to cases such as Chen and Zhu, and the pressures that the Irish Government argued they were putting on the CTA.Footnote ⁷⁶ Notwithstanding this amendment, most people born in Northern Ireland remain automatically entitled to both UK and Irish citizenship. Indeed, the Belfast/Good Friday Agreement (GFA) acknowledges the “birthright” of the people of Northern Ireland to identify and be accepted “as Irish or British, or both, as they may so choose.”Footnote ⁷⁷

This birthright creates a distinct body of Irish citizens living within the UK whose rights derive from the GFA and not from the CTA. Some measures, such as the UK Civil Service Nationality Rules,Footnote ⁷⁸ already divide Irish citizens based upon whether or not they form part of the people of Northern Ireland.Footnote ⁷⁹ Irish citizens who belong to the people of Northern Ireland are EU citizens and will remain so after Brexit. But because such individuals were born in the UK and have not moved to another EU Member State, they find it difficult to assert that they have activated some of their rights under EU law.Footnote ⁸⁰ The UK Government moreover insists—drawing upon the definition of a UK citizen in British Nationality Act 1981Footnote ⁸¹—that such individuals are prima facie also UK citizens, and that as dual nationals living in their “home” country, they cannot benefit from EU free movement law.Footnote ⁸²

This position is being challenged in the ongoing De Souza litigation,Footnote ⁸³ in which a Northern Ireland-born woman who identifies as Irish is seeking to rely on her EU citizenship to secure the residency of her spouse, a third-country national. The Home Office contested these claims on the basis that to claim EU citizenship rights relating to third-country national spouses, Emma de Souza would have to first renounce her UK citizenship—a status which she does not recognize and regards as incompatible with her GFA birthright. The Upper Tribunal made short work of Emma de Souza’s birthright claims, noting that if the parties to the GFA had “intended the concept of self-identification necessarily to include a person’s ability to reject his or her Irish or British citizenship, it is inconceivable that the provisions would not have dealt with this expressly.”Footnote ⁸⁴ Such a conclusion demonstrates little appreciation for the open-textured quality of peace agreements such as the GFA, which is necessary to allow them to address contentious subject matter.

Despite its Tribunal victory, the UK Government responded to the furor surrounding the case by pledging to treat people of Northern Ireland in the same manner as Irish citizens resident in the UK under the CTA for the purpose of rights of third-country spouses.Footnote ⁸⁵ The subsequent adjustments to the immigration rules were applied to all of the people of Northern Ireland, independent of how they identify, in light of the GFA’s parity-of-esteem requirements.Footnote ⁸⁶ Under these adjustments, third-country spouses and dependents of members of the people of Northern Ireland became eligible to protect their residence rights as if they were doing so with regard to an EU citizen under the EU Settlement Scheme.Footnote ⁸⁷ Even if the UK Government’s response was grudging and delayed, the episode illustrates how the GFA’s obligations can exert a pull on public policy beyond what judges have ruled to be their effects in domestic law. The new rights are, however, temporary, because the EU Settlement Scheme is only open to applications until June 2021 and, as we shall see, this response has not settled Emma de Souza’s claims.

The Irish authorities are also weighing up whether to differentiate between these groups of Irish citizens resident in the UK after Brexit (those who belong to the people of Northern Ireland and those who do not). This is demonstrated by the Taoiseach’s announcement that Ireland would—in the event of a no-deal Brexit—establish an alternate provision to the European Health Insurance Card (EHIC) for the people of Northern Ireland and EU citizens resident in Northern Ireland, but not for Irish residents of Great Britain.Footnote ⁸⁸ The imperative for the UK Government must nonetheless remain to provide for broadly similar rights and entitlements to both groups. Failure to do so will generate not only the administrative burdens of distinguishing between different groups who self-identify as Irish citizens on the basis of the rights and entitlements at issue but also inevitable high-profile legal challenges drawing upon the post-GFA protections for equality of treatment.Footnote ⁸⁹

I. UK Domestic Law

Brexit, it is trite to say, necessitates a major overhaul of the UK statute book.Footnote ¹⁰² Part of this effort updates domestic legal provisions relating to Irish citizens and their status in the UK. The European Union (Withdrawal) Act 2018 establishes a default rule whereby EU law and related UK measures are retained after Brexit, with fresh legislation being required to move away from this position.Footnote ¹⁰³ One such piece of legislation, the Immigration and Social Security Co-ordination (EU Withdrawal) Bill, has been repeatedly delayed, abandoned, and restarted because of the saga over the Withdrawal Agreement’s ratification and, latterly, the Covid-19 crisis. When it is eventually enacted, it will end the application of EU freedom of movement law for EEA and Swiss citizens.Footnote ¹⁰⁴

Against this backdrop of curtailing freedom of movement, specific saving provisions are included within the legislation for Irish citizens, clarifying how they are to be treated for immigration purposes after Brexit. At present, the Immigration Act 1971 formally applies exemptions from immigration control only for Irish citizens making “local” journeys, meaning those between the constituent parts of the CTA.Footnote ¹⁰⁵ This provides for a poor fit with contemporary international travel, and EU free movement law produced a situation whereby these statutory point-of-departure rules became inoperative.Footnote ¹⁰⁶ As soon as the UK moves to restrict freedom of movement, it therefore also becomes necessary to amend the 1971 Act to clarify that Irish citizens do not require “leave to enter or remain in the UK,” as a general rule.Footnote ¹⁰⁷

The Immigration Bill’s proposals furthermore clarify the exceptions to free movement into the UK for Irish citizens, in the form of deportation orders, public good exclusions, and international law exclusions.Footnote ¹⁰⁸ Deportation of Irish citizens has been possible under UK immigration law since 1962.Footnote ¹⁰⁹ Under the Immigration Act 1971, a narrow class of Irish citizens was exempted from deportation from the UK, establishing that all others are subject to deportation.Footnote ¹¹⁰ Irish citizens currently enjoy protections under EU free movement law, which explicitly sets a high threshold for a host Member State to deport an EU citizen to their home country.Footnote ¹¹¹ An EU citizen must be a current threat to public security or policy in order to be deportable, and deportation decisions must take account of the duration of residency in the host State.Footnote ¹¹² The Immigration Bill, as drafted, provides that the UK Home Secretary will be able to order the deportation of an Irish citizen if this is considered to be necessary in the public interest.Footnote ¹¹³ This provision sits uneasily with existing policy, contained within a ministerial statement, whereby “Irish citizens will only be considered for deportation where a court has recommended deportation in sentencing or where the Secretary of State concludes … the public interest requires deportation.”Footnote ¹¹⁴ Existing regulations, moreover, prevent the UK Home Secretary’s power to deport foreign prisoners at the end of their sentence from applying to Irish citizens.Footnote ¹¹⁵ Under Irish law, by contrast, UK citizens are explicitly exempt from deportation in any circumstances, illustrating the limits to reciprocity across the CTA jurisdictions.Footnote ¹¹⁶

The Bill’s deportation provisions, moreover, do not take account of the special position of Irish citizens who are from Northern Ireland.Footnote ¹¹⁷ The Bill describes a general power to deport Irish citizens but does not mention the status of individuals who form part of the “people of Northern Ireland” and exercise their GFA “birthright” by choosing to identify as Irish alone. As we have already seen in the De Souza litigation, the Home Office is insistent that such individuals are automatically UK citizens, whether they choose to identify as such or not.Footnote ¹¹⁸ The De Souza appeal, which would have addressed these issues, was dropped in May 2020 (after the success of their campaign with regard to the rights of third-country national dependents of the people of Northern Ireland). This outcome does not, however, get the UK Government out of the woods. Clause 2 makes no allowance for those among the people of Northern Ireland who took the advice that the Home Office gave to Emma De Souza and renounced this underlying UK citizenship.

As a result of these concerns the UK Government faced amendments in Committee to the first version of the Immigration Bill that aimed to protect such Irish citizens from Northern Ireland. To see these off, Theresa May’s Immigration Minister was obliged to provide assurances that, given “the citizenship provisions in the Belfast agreement, we would consider any case extremely carefully and not seek to deport a person from Northern Ireland who is solely an Irish citizen.”Footnote ¹¹⁹ These assurances could provide the basis of future efforts to resist deportation based on these provisions. But they were not incorporated into the Bill’s text when it was reintroduced into the Commons after Johnson’s 2019 election success (and previous mentions of the GFA were excluded from the Bill’s Explanatory Notes). Much will thus depend on whether these assurances are reaffirmed. In summary, this legislation takes some steps to give effect to the rights to enter and reside associated with the CTA, but its terms fail to take express account of the unique status of the people of Northern Ireland—necessitating patching up through ministerial statements—and might in some circumstances facilitate deportation of Irish citizens from the UK, especially as they will no longer enjoy EU law’s protections post-Brexit.^{Footnote 120}

II. The UK–Ireland Convention on Social Security

If a particular dimension of the operation of CTA has been all but completely usurped by EU mechanisms, it is the coordination of social security benefits between Member States. To support free movement of EU citizens, the Member States have all agreed to make many social security benefits portable; accumulations travel with EU citizens to different Member States, as a lack of portability would discourage anyone from exercising free movement.Footnote ¹²¹ Social security coordination is therefore an activity which is often associated with the CTA, but which has long operated largely under the auspices of EU law.

That said, the portability of social security entitlements is deep and more organized than other aspects of the CTA. Between 1960 and 1971, Ireland and the UK concluded a series of agreements on aspects of social security, which were consolidated into a Convention on Social Security in 2004.Footnote ¹²² These bilateral arrangements do not, however, provide for more intense coordination between the UK and Ireland than the EU social security coordination regime. Instead, they provide for an extended zone of application. Notwithstanding the UK and Ireland’s shared EU membership, the 2004 Convention was necessary to extend social security cooperation to cover the Crown Dependencies—and to cover their citizens in Ireland and the UK—which are also part of the CTA but outside the ambit of EU law.Footnote ¹²³ The effects of these developments can be seen in UK unemployment benefits, which count residence in any part of the CTA towards their “habitually resident” requirement.Footnote ¹²⁴

With the then-presumptive Brexit date of March 29, 2019 looming, the UK and Ireland had to confront the extent to which their bilateral social security coordination rested on EU law. They agreed a new Convention on Social Security.Footnote ¹²⁵ The UK Parliament’s EU Committee summarized its effect:

In Ireland, this Agreement was rapidly reflected in primary legislation scheduled to enter into force upon Brexit.Footnote ¹²⁷ The oversight of the specialist EU Committee notwithstanding, this Agreement received little attention in UK Parliament, paralyzed as it was by Theresa May’s efforts to secure the ratification of the UK–EU Withdrawal Agreement. It was ratified without debate and quietly actioned by Order in Council,Footnote ¹²⁸ separating Irish citizens using the CTA from the arrangements for other EEA and Swiss citizens, which were being drawn up under the Immigration and Social Security Co-ordination (EU Withdrawal) Bill. The fact that the UK and Ireland concluded this specific new agreement prompted the EU Committee to wonder whether it needed to be supplemented by further legislation or additional international agreements in order to replicate other aspects of EU law that the CTA relies upon. It cautioned, however, that it “is unclear … whether a series of patchwork CTA agreements will provide the assurances that are needed on such a sensitive matter.”Footnote ¹²⁹ The stage was thus set for further CTA developments.

III. The CTA Memorandum of Understanding

For all of this preparatory work, the subsequent conclusion of the CTA MoU on May 8, 2019 would appear to be something of an anti-climax. The MoU was not intended to recast the CTA but rather “reaffirms the arrangement … in relation to the Common Travel Area … and the associated reciprocal rights and privileges enjoyed by British and Irish citizens in each other’s state.”Footnote ¹³⁰ The subsequent provisions set out what the UK and Ireland understand the CTA to be, and the “associated reciprocal rights and privileges” that accompany it. The MoU is drafted to make it clear that both parties agree that the relevant arrangements already exist, and are being recapitulated in the MoU, because it is “desirable to provide a contemporary articulation” of them.Footnote ¹³¹ The associated rights recognized in the MoU are free movement, a right to reside, the right to work, the right to healthcare, the right to social protection—or social security, the right to social housing, the right to education, and the right to vote. This effectively mirrors the list of CTA-related rights previously identified by the UK GovernmentFootnote ¹³² and could therefore be interpreted as containing no substantive extensions to the CTA.

Nonetheless, it is significant that both countries formally acknowledge that the CTA is not simply a free-movement zone and explicitly tie the reciprocal rights for each other’s citizens to the CTA. It is no longer an act of conflation to talk of these as being CTA rights. Both parties commit “to ensuring that any necessary steps are taken to give effect to” the CTA rights, and identify in particular that domestic legal responses “and further, more detailed, bilateral agreements” may be needed to protect these rights.Footnote ¹³³ The UK and Ireland further agree to hold annual meetings between senior officials regarding the MoU, presumably to consider any aspect of the functioning of CTA-related rights in practice.Footnote ¹³⁴ These arrangements, however, remain diplomatic in nature; the MoU provides for no remedial mechanism if disagreements arise in one of these meetings, and expressly recognizes that it “is not of itself intended to create legally binding obligations.”Footnote ¹³⁵ Whereas the Convention on Social Security is a binding agreement under international law, the CTA MoU thus merely reflects the parties’ “common understanding” of the CTA’s requirements. As such, the MoU required no ratification process before the UK Parliament and was not subject to any debate amongst legislators.Footnote ¹³⁶

IV. The New CTA: Brexit-Proof?

We have seen three different forms of “Brexit-proofing” to date: Domestic legislative actions in the UK and Ireland, a binding international agreement on social security, and a bilateral political commitment to the CTA more generally. These efforts have been focused upon the CTA-related rights to reside and work, and to access social security protections. This has not been a process intended to strengthen rights but one to provide an alternate legal basis to EU law. Although other CTA rights have yet to be addressed by bilateral arrangements at the time of writing, further activity is clearly envisaged. In January 2019, Ireland’s Minister for Foreign Affairs informed the Dáil that “[b]ilateral arrangements as appropriate to each area of the CTA, will be concluded in due course and at the appropriate time.”Footnote ¹³⁷ The implication is that a broad range of CTA measures could follow.

Ireland’s Brexit legislation, moreover, permits the Health Minister to make orders “to continue in being or carry out any reciprocal or other arrangements in relation to health services which were in operation between the State and the United Kingdom immediately before the withdrawal of the United Kingdom from membership of the European Union.”Footnote ¹³⁸ This suggests that arrangements have been made with the UK for steps to be taken, following Brexit, to protect reciprocal health care access for each other’s citizens. Ministers confirmed that these provisions envisaged a no-deal scenario, when the rights of Irish citizens resident in the UK would not be covered by any overarching arrangements for settled EU citizens.Footnote ¹³⁹ But such statements also highlight the patchwork of Ireland-specific and so-called EU “settled status” measures which could apply to Irish residents of the UK after Brexit. The closed-room intergovernmental dealings to which these measures alludeFootnote ¹⁴⁰ might be entirely in keeping with the history of the CTA, but they provide precious little reassurance to affected individuals. We must, therefore, evaluate whether this ongoing activity is sufficient to sustain the CTA-related rights after Brexit.

I. Replacing the Irreplaceable?

Under an orthodox account of the UK’s dualist legal order, the UK’s international agreements do not affect rights and obligations within the UK’s domestic jurisdictions; short of the UK Parliament incorporating treaty provisions into domestic law, they are not enforceable before domestic courts.Footnote ¹⁴¹ Even then, it is not the treaty but the statute that is being enforced.Footnote ¹⁴² EU law, however, is distinct in the UK’s domestic legal system because of its overarching principles of direct effect and supremacy.Footnote ¹⁴³ In order to join the EEC, the UK was obliged to make the provisions of the EEC legal order enforceable before domestic courts under certain conditions.Footnote ¹⁴⁴ It was also obliged to accept the Commission’s enforcement action as an oversight mechanism, whereby the Commission can bring any Member State before the CJEU if they are failing to comply with either the letter or the spirit of EU law.Footnote ¹⁴⁵ On a constitutional level, Theresa May’s administration conceived of Brexit as a means of ending these impositions: “Whilst Parliament has remained sovereign throughout our membership of the EU, it has not always felt like that.”Footnote ¹⁴⁶

Once Brexit stops the enforceable protections—provided by the EU legal order—applying within UK law, bilateral arrangements concluded between the UK and Ireland to cover Brexit’s aftermath will inevitably be a poor substitute for EU law.Footnote ¹⁴⁷ This is not to say that EU law is currently working effectively for EU citizens attempting to rely upon it in the UK’s domestic legal systems. As Charlotte O’Brien has highlighted, even though “EU citizenship was always extremely limited in terms of the social protections it offered EU migrants,” those limited rights have been implemented and applied in the UK in ways that has made them even more difficult to access and exercise.Footnote ¹⁴⁸ For instance, UK courts have tended to interpret domestic implementing legislation of EU citizenship rights in narrow and conflicting ways.Footnote ¹⁴⁹ If we consider the future of the CTA post-Brexit, it is worrying that O’Brien already finds that because the EU social security coordination regulation is “complex, contradictory and incomplete,” it has resulted in “imaginative and exclusionary domestic interpretation” in the UK courts.Footnote ¹⁵⁰ There is no reason why UK courts would interpret related coordinating legislation, such as the Order in Council that implements the Convention on Social Security, in a less exclusionary manner after Brexit.

Even under the Withdrawal Agreement, the protections afforded by the oversight of the Commission and CJEU will lapse in the medium term. The enforceability of affected rights will therefore inevitably diminish in practice. Indeed, in the broader context of settled-status rights for EU citizens, the EU has conceded that the protections afforded by its legal order cannot be replicated in a third country; the rights agreed upon under the Withdrawal Agreement will be enforced by the Commission in the EU—for UK citizens resident there—and, after a transition/implementation period, by a national body—the Independent Monitoring Authority—in the UK, for resident EU citizens.Footnote ¹⁵¹ Given that an element of enforceability is lost even under the Withdrawal Agreement, bilateral arrangements between the UK and Ireland make for even less of a safeguard.

II. The Nature of the New CTA Arrangements

Ireland and the UK have used a range of approaches to secure the CTA after Brexit. The Convention on Social Security is a bilateral international treaty covering some CTA-related rights, enforceable by the state parties through arbitration. The first step in any dispute over the Convention is for the state parties to make “all reasonable efforts” to resolve these through diplomatic channels, but arbitration is provided for as a follow-up option.Footnote ¹⁵² The outcome of arbitration will be “binding on both parties.”Footnote ¹⁵³ Whereas a violation of EU measures coordinating social security could be challenged before a UK or Irish court by affected private individuals, the Convention’s arbitration provision is a tool employed at the state level, and various issues could dissuade one of the states from taking up an individual’s complaints. On a purely diplomatic level, Ireland might be reluctant to commence arbitration against the UK, as a larger trading partner, unless significant violations were at issue.Footnote ¹⁵⁴

The overarching CTA MoU, by contrast, is something short of a bilateral treaty. As Brian Gormally, Director of the Northern Ireland-based NGO, the Committee for the Administration of Justice, observed before the Dáil: “The problem with memoranda of understanding is that they are not, generally speaking, legally enforceable.”Footnote ¹⁵⁵ His deputy, Daniel Holder, elaborated upon these concerns:

The name of an international agreement is not particularly significant in determining its nature. While MoUs are often non-binding agreements, if the parties had intended to make its terms enforceable, the CTA MoU could have provided for bilateral obligations.Footnote ¹⁵⁷ Yet the MoU itself leaves no room for interpretation, stressing that it does not produce “legally binding obligations.”Footnote ¹⁵⁸ It can also be contrasted with the UK’s MoUs, with countries such as Jordan and Algeria, regarding the deportation of individuals suspected of involvement in terrorism to their countries of origin. Each of these MoUs was intended to constitute “an exceptionally strong political commitment” against the country of origin practicing torture, and their common understandings were undergirded by monitoring arrangements and specific rules for withdrawal.Footnote ¹⁵⁹ The CTA MoU, by contrast, provides for no such formal mechanisms, and so it becomes necessary to consider whether these new arrangements will be of any value in domestic litigation after Brexit.

III. Enforceability in Domestic Litigation

Question marks remain over whether the new CTA arrangements can provide any meaningful assistance to individuals seeking to challenge alleged breaches of their terms before the domestic courts in the UK—or, indeed, Ireland. The first distinct issue is the value of the Convention on Social Security. As we have seen, this treaty has been brought into effect in the law of Ireland and the UK through domestic measures. In such circumstances, the UK courts have long accepted the principle that statutes or statutory instruments designed to give effect to an international obligation “are to be construed, if they are reasonably capable of bearing such a meaning, as intended to carry out the obligation.”^{Footnote 160} Irish claimants should thus be able to rely upon the Convention to secure their interests within UK social security law; indeed, the terms of the incorporating Order in Council explicitly provide that a range of social security legislation is “modified to the extent required to give effect to the provisions contained in the Convention.”Footnote ¹⁶¹ In Ireland, the specific amendments to the Social Welfare Consolidation Act 2005, adopted to give effect to the Convention, would similarly be interpreted in light of the Convention’s provisions.Footnote ¹⁶² The above concerns about UK policy makers limiting the effect of the relevant provisions aside, individuals will be able to directly rely on these domestic measures before domestic courts.

By contrast, the CTA MoU provides comparatively little support for any individual seeking to use it to protect the CTA’s “reciprocal rights and privileges” in litigation in Ireland or the UK.Footnote ¹⁶³ Some recent decisions suggest that both countries’ judges are becoming more receptive towards considering unincorporated treaties and other international arrangements, especially where individual rights are at issue, in the application of relevant domestic law. For Lord Kerr, such consideration is not a backdoor incorporation but “is merely allowing directly relevant standards to infuse our thinking about what the content of the domestic right should be.”^{Footnote 164} In Ireland’s Supreme Court, Justice Barrington, dealing with the then-unincorporated European Convention on Human Rights, similarly opined that “it may be helpful to an Irish court to look at the Convention when it is attempting to identify unspecified rights [under Ireland’s Constitution].”Footnote ¹⁶⁵ The UK House of Lords, moreover, relied upon the MoU concluded between the UK and Jordan to determine whether the UK had fulfilled its obligations under the Human Rights Act 1998 in the deportation of Abu Qatada.Footnote ¹⁶⁶ As such, the domestic courts could opt to treat the CTA MoU as something akin to an explanatory memorandum for domestic laws—which, in practice, give effect to aspects of the CTA or which provide for special treatment of Irish citizens in UK law—or vice versa—such as the Immigration Bill currently before the UK Parliament. But the problem remains that domestic courts are not obliged to consider the MoU as an interpretative tool in the way that they are currently obliged to read any UK law implementing EU obligations in line with the original EU legislation.Footnote ¹⁶⁷ They may, moreover, be reluctant to place particular weight on the MoU, on the basis that they are dealing not with a formal treaty but a mere understanding of the CTA’s operation.

The distinction between the MoU and a binding treaty also has specific enforcement consequences within the UK’s devolution settlement. The Scottish, the Welsh, and Northern Ireland institutions are all restricted in their legislative and executive competences, through statutory obligations to respect the UK’s commitments under international law.Footnote ¹⁶⁸ As a result, due to its competences with regard to social security, the Scottish Parliament had to pass legislation covering the Social Security Convention between Ireland and the UK.Footnote ¹⁶⁹ These obligations, however, do not apply to the non-binding terms of the CTA MoU. In the UK’s increasingly complex jurisdictional landscape, restrictions upon supposedly reciprocal rights could therefore emerge from the devolved institutions. In this regard, it is worth remembering that some of the most egregious breaches of reciprocity prior to Ireland and the UK joining the EU came as a result of legislation passed by the Unionist-dominated Northern Ireland Parliament, which functioned between 1922 and 1972.Footnote ¹⁷⁰

Finally, the Northern Ireland Human Rights Commission’s Chief Commissioner has suggested that the new CTA MoU could form the basis of legitimate expectations for individuals, permitting them to institute judicial review challenges in the UK and Ireland if executive actors sought to take steps which diluted the reciprocal rights arrangements that it covers.Footnote ¹⁷¹ The concept of legitimate expectations functions similarly in the administrative law of Ireland and the UK, permitting claimants who acted reasonably—in reliance on public authorities’ promises or practices—to challenge attempts by the public authority to resile from that promise or practice.Footnote ¹⁷² The aim of the courts is to ensure that public bodies “deal straightforwardly and consistently with the public.”Footnote ¹⁷³ But in the UK the courts have been reluctant to treat international agreements as the basis for legitimate expectations. Lord Justice Laws, for one, was unequivocal in his rejection of this idea, asserting that the UK’s domestic courts “must not be seduced by humanitarian claims to a spurious acceptance of a false source of law.”Footnote ¹⁷⁴ Even if the courts became willing to reconsider this position, the CTA MoU is a different proposition from the unincorporated treaties Lord Justice Laws had in mind. Its non-binding nature calls into question whether its terms could ever be treated as sufficiently committal to amount to a promise to affected individuals within the terms of legitimate expectations jurisprudence.Footnote ¹⁷⁵ Therefore, legitimate expectations doctrine is highly unlikely to provide a basis for sustaining domestic law claims based upon the CTA.

IV. Coverage

Beyond issues with enforcement, the legislative materials being developed to address the status of Irish citizens in the UK after Brexit do not replicate all of the rights they currently enjoy as EU citizens. In particular, not all Irish citizens will enjoy the same rights to bring third-country spouses into the UK. Irish citizens who have moved into the UK under the CTA will be able to protect such rights under the settled-status regime covering EEA and Swiss citizens, if these provisions of the Withdrawal Agreement are ratified.Footnote ¹⁷⁶ But, as discussed above, Irish citizens who are part of the people of Northern Ireland are excluded by the UK Government from the proposed settled-status measures for EU citizens, except with regard to the concession covering their third-country spouses and dependents.Footnote ¹⁷⁷ Irish citizens who were born in Northern Ireland will be, in this material regard, less protected and more restricted in their ability to claim rights derived from EU law than Irish citizens born elsewhere, even when both groups will be resident alongside each other in post-Brexit Northern Ireland. This proposition is difficult to square with the GFA’s commitments to ensuring that the people of Northern Ireland can fully express their British or Irish identities.Footnote ¹⁷⁸ Under the Withdrawal Agreement, there are thus distinct advantages—in terms of the substantive rights on offer and available enforcement mechanisms—for Irish citizens who can register for settled status to do so, rather than rely solely on CTA mechanisms.

The Irish Government, by contrast, has not chosen to operate a settled-status scheme for UK citizens resident in Ireland. UK citizens will therefore be able to benefit from the Withdrawal Agreement, including rolling over their accumulated EU residency rights in Ireland, without the need for registration. Unlike the CTA, these rights are not based on “equivalence” with home citizens, and under the Withdrawal Agreement, more generous provisions derived from EU free movement law—particularly with regard to non-EEA spouses and family members—are retained.Footnote ¹⁷⁹ For such families, who rely upon the rights derived from EU free movement law, the conclusion of a Withdrawal Agreement therefore took on particular importance.Footnote ¹⁸⁰ For other UK citizens resident in Ireland, the CTA should suffice to support many of the needs of day-to-day life but by no means all. The CTA does not, for example, secure the recognition of the UK-issued driving licenses belonging to people resident in Ireland.Footnote ¹⁸¹ In the summer of 2019, with the threat of a no-deal Brexit apparently looming, urgent public information campaigns in Ireland sought to persuade such drivers to immediately exchange their UK licenses for ones issued by Ireland.Footnote ¹⁸² On this basis, the months after the Brexit transition/implementation period ends will undoubtedly reveal the myriad ways in which, notwithstanding the existence of the CTA, EU law has facilitated movement between the UK and Ireland.

V. Covid-19

Within weeks of the UK leaving the EU on January 31, 2020, Europe was plunged into the Covid-19 crisis. As the UK and Ireland went into varying states of lockdown to combat the pandemic, the CTA came under renewed strain. On one level, the crisis has confirmed the importance of the CTA, with both countries maintaining travel connections between them, even as borders across the Schengen Area closed to non-essential travel. Ireland chose not to align with EU measures restricting non-essential travel from third countries, to enable it to maintain the CTA.Footnote ¹⁸³ When asked to justify Ireland’s approach with regard to cross-border travel from Northern Ireland, the Taoiseach raised the issue of travelers on internal UK flights between London and Belfast: “The only way we could have stopped people on that flight travelling to just this jurisdiction would be to seal the land border between Northern Ireland and Ireland. We are certainly not going to do that.”Footnote ¹⁸⁴

This policy decision has meant that Ireland’s restrictions on travel—to attempt to inhibit the spread of the virus—have not been applicable to people resident in Northern Ireland, potentially reducing their effectiveness. Moreover, although the CTA has so far been maintained through the crisis, this is not the same as saying that Ireland and the UK have acted in a coordinated manner when it comes to its requirements. There was little discernable high-level intergovernmental communication on the management of the CTA prior to the middle of May 2020, and even this communication did not produce immediate coordination. The UK, for example, has refused to apply quarantine requirements on travelers entering the UK on direct flights from Ireland. Ireland, for its part, has imposed quarantine restrictions on travelers on flights from the UK.Footnote ¹⁸⁵ Such divergences flag up the contingent nature of any concept of CTA reciprocity. The CTA does not envisage complete alignment between the jurisdictions that it covers, and even if it did, it imposes no legally enforceable obligations. Indeed, the very fact that any restrictions on travel across Ireland’s land border are so firmly off the table, notwithstanding this crisis, illustrates the fragility of the CTA, not its strength.