The prospect of a Brexit deal has foundered on the issue of the Northern Ireland border. Duncan Morrow (Ulster University) explains why the delicate relationship between Ireland and its dysfunctional neighbour depended on the EU’s fluid borders to survive. Any effort to ‘do’ Brexit on Johnson-DUP terms means that devolution in Northern Ireland will ‘die’, forcing an unpopular Westminster government to take direct control amid huge social, political and economic turmoil.

The crisis of legitimacy over the right of the British state and its supporters to exercise authority anywhere on the island of Ireland has always afflicted any efforts to govern Northern Ireland. In the democratic era, Irish anti-imperialism crystallised into an unquenchable demand for independent Irish statehood as a ‘nation once again’. But democracy also mobilised the masses in the north-east, where Ulster Unionists successfully organised a popular ‘counter-militia’ threatening violent resistance to any move to devolve power to Dublin, let alone independence, and proclaimed undying loyalty to the Empire and their birthright within it.

From the perspective of Westminster in 1920, Northern Ireland was the pragmatic answer to the conundrum. But it was always more expediency than principle. When Northern Ireland finally settled into its six county boundary, the border did not so much divide Unionist from Nationalist Ireland as separate overwhelmingly nationalist Ireland from the British-Irish interface in the north. Simultaneously, and less obviously, a new devolved half-‘border in the Irish Sea’ stealthily contained Great Britain from Northern Ireland affairs. It created a United Kingdom where the vast majority were increasingly and blissfully ignorant of both the origins and consequences of British statecraft.

The ‘two borders’ combined to insulate this contentious remnant of British-Irish popular confrontation into its own ‘place apart’. Northern Ireland was left to itself, a quarantine for the historically disturbed, ostensibly fighting over the Empire while rerunning the Reformation. Unionists held power and demanded recognition of their legitimacy, while Nationalists, deeply alienated in their own home, refused to oblige.

When tensions escalated into violence in the late 1960s, the British and Irish governments were forced into massive efforts to prevent internal collapse and the wider spread of violence. By the 1980s both concluded that only a common front, eased and facilitated by deepening co-operation as equal members of the European Community, could bring significant change. Thirteen years of intense negotiations followed, during which both the United States and the European Union acted as critical ballast in a fragile experiment.

At the heart of the Good Friday Agreement in 1998 was a radical – but implicit – compact on sovereignty in Ireland. Its key achievement was to finally establish a basis for the legitimacy of government in Northern Ireland. This remarkable feat was achieved in part by the historic accident that radical experiments in theory – like changes in sovereignty, citizenship and rights – became invisible and painless in practice within the functional reality of the EU, where crossing borders was encouraged and other changes were already implied or in place. Mutual citizenship was extended in a wholly unique way, equality of treatment for citizens and non-citizens of the sovereign state was enshrined and internal bodies were interdependent with cross-border bodies, all without any significant disruption.

In this context, the lethal and deeply rooted concept of ‘legitimate targets’ was set aside in favour of ‘purely peaceful and democratic means’. The UK-Ireland border was transformed from a symbol of contention into a model of co-operative inter-nationalism. Army checkpoints disappeared and hundreds of border roads reopened. Armed groups melted into the background. The Irish President visited the North as if it was already a normal part of the jurisdiction. Meanwhile devolution in the UK went mainstream and Northern Ireland was no longer so distinctively ‘odd’, but plausibly part of a multi-dimensional reform of the whole state. Restrictions on movement to Britain were reduced with the softening of the Prevention of Terrorism Act. There were still two ‘borders’ of sorts, but now they were ‘boundaries’, not security fences. Royal and presidential visits sealed a remarkable reboot of British-Irish relations that few in the 1970s dared hope for. Set against the slaughter of the Troubles, it was immeasurably better than the past.

Perhaps complacency accounts for why so few took seriously the potential for polarisation for Northern Ireland that Brexit carried within it. Certainly few in any jurisdiction appear to have understood how critically the Agreement depended on fundamental British-Irish partnership. But the ‘ecosystem’ logic (‘nothing is agreed until everything is agreed’) behind the Agreement is also its vulnerability. The Agreement becomes exposed to total collapse when core parts of the ecosystem fail.

In retrospect, the implications of the UK’s land border with ‘Ireland’ for ambitions for a clean break from ‘Europe’ were only superficially addressed in the referendum campaign. Neither campaigners nor voters dwelled on how Brexit’s implicit demand for hard borders contradicted the subtle status of Northern Ireland’s boundaries, and automatically reinvigorate the issue of identity. In turn, this would re-inflame the dormant question of the legitimacy and viability of Northern Ireland. Promoted as a way to ‘take back control’ from EU bureaucracy, few grasped that Brexit potentially also disabled the baseline partnership of the UK and Ireland, and with it the fundamental basis on which any semblance of control had been possible in Northern Ireland.

But now the implications of this contradiction have escalated to become the defining crisis of the Brexit psychodrama. Hard borders to ‘Europe’ mean hard borders to Ireland. But hard borders in Ireland will mean the collapse of Britain’s arguably most significant post-colonial achievement.

By now almost every way to resolve the contradiction has been offered and rejected. The logic of a ‘customs border in the Irish Sea’ was interrupted on numerous occasions by the DUP after they captured the balance of power in Westminster in 2017. Theresa May’s ‘solution’ was to save the Union by delaying Brexit for everyone, but only at the cost of revolt by the Brexiters in her own party. And still, without commitment to an open border in Ireland, the EU would not play.

Armed with a commitment to ‘do or die’ before Halloween, the Johnson government has proposed that Northern Ireland should stay within the Single Market in an all-island regulatory zone while leaving the Customs Union. This will require some checks on goods entering Northern Ireland from Great Britain and between both parts of Ireland. But the prospect of two borders replacing no borders, businesses apoplectic about the bureaucracy that will replace “frictionless trade”, the risk of a ‘smuggler’s paradise’ and the unilateral award of a one-party veto to Unionism dismayed almost everyone outside the DUP, including other Unionists.

In the absence of a workable solution, the threat, if there is one, comes not from security but from politics – or at least from the absence of a viable political process. The fear which haunts Northern Ireland is a legacy of the 1960s, when protest escalated to confrontation in the context of a crisis of legitimacy. Violence which nobody had even contemplated in 1967 suddenly outgrew its container and took on a tragic dynamic after 1969. No political party could either predict or control it.

There is widespread consensus that neither republican nor loyalist ultras have the capacity or any support at present for a return to mass killing. There is some cause for hope in the fact that Northern Irish voters approved the Agreement but rejected Brexit, suggesting the Agreement has greater legitimacy. But in practice, any effort to ‘do’ Brexit on Boris-DUP terms means that devolution in Northern Ireland will ‘die’, forcing an unpopular Westminster government believed by the majority to have destroyed Northern Ireland’s best chance for change, to take direct control amid huge social, political and economic turmoil. The decisions to extend abortion legislation and gay marriage to Northern Ireland can rely on popular support. But in a context where the Agreement has greater legitimacy than Brexit, every controversial decision, even on apparently unrelated issues, has at least the potential to become a constitutional crisis.

This is what happens when small border zones are treated as expendable collateral in the supposedly more important affairs of larger states. But it is a bleak prospectus for a place which has never shaken off historic hostilities and can only exist if the ecosystem around it enables it to do so.

This post represents the views of the author and not those of the Brexit blog, nor LSE.