A supposedly 'hard' border between Northern Ireland and the Republic after Brexit is unfit for purpose – it leaks like a sieve for 'controlling' immigration and creates a smugglers' bonanza. What's the answer? Professor James Anderson examines the impact of Brexit on Ireland.

James Anderson is Emeritus Professor of Political Geography in the Senator George J. Mitchell Institute for Global Peace, Security and Justice, and a founder-member of the Centre for International Borders Research at Queen's University Belfast.

Ireland could suffer most from Brexit – Northern Ireland more than other parts of the UK, the Irish Republic more than the rest of the European Union. The issues crystallise in the question of borders. In the North a clear 56% majority, including about a third of unionists, voted Remain, and very few people even among pro-Brexit voters want a 'hard' border between the North and South. But few believe British promises about a 'soft' electronic border. The Brexit imperative of 'stopping immigration' demands a hard border, as does an EU external frontier, and the real question is where?

The North-South land border is totally 'unfit for purpose', attempting to 'harden' it would create a mess of economic, social and political problems, but – the good news – solutions are available.

A paradise for smugglers and paramilitaries

Based partly on medieval ownership patterns, the land border meanders around for over 300 miles through towns, hinterlands, local communities, farms and occasionally houses. Even when highly militarised in the Troubles, with 200 cross-border roads closed, it leaked like a sieve. So, irrespective of what happens in Ireland, the actual hard border for 'stopping immigration' will be the sea around Britain and its seaports and airports connecting with Ireland and the continent (though an independent Scotland within the EU would require additional measures). Similarly, the border for freight should be at ports and airports. They already have secure infrastructures for handling goods, whereas a supposedly hard land border would in reality be a smuggler's paradise.

Attempting to harden it would sever the free trade between North and South, their cross-border production and supply chains, and substantially integrated but fragile economies. It would delay freight movements, clog up border roads, and disrupt travel for 30,000 cross-border commuters and all the other thousands who live their lives on both sides or cross occasionally to socialise, shop or use shared services. Politically it would provoke mass protests and civil disobedience. More ominously, it would undermine a 'peace process' explicitly based on cross-border institutions and minimising the border, and only paramilitaries would benefit. Building customs facilities along the border would be an open invitation for the 'dissident republicans' to copy the IRA's 1950's Border Campaign attacking border posts and personnel. That could boost their presently small numbers, in turn boost opposing unionist paramilitaries and conceivably re-ignite at least a mini-version of the Troubles.

Obstacles and omens

Avoiding the smuggler and paramilitary paradise won't be easy. Mrs May's priorities lie elsewhere; the administrations in Belfast, Dublin and London are currently in flux. The North's largest unionist party, the DUP, is pro-Brexit and out-of-step with the 56% Remain majority; and there has always been a sizeable fringe of extremely nationalistic right-wing unionists who prefer nostalgic fantasies of British sovereignty to actually dealing with economic and social problems.

However, there are some good omens for retaining island-wide free trade and avoiding a hard land border. The EU wants to solve this issue before the trade talks with Britain (which could of course fail). It has poured millions into the cross-border 'peace process', and Ireland has already pioneered hybrid border-crossing institutions to deal with practical problems of conventional sovereignty.

Demands for Northern Ireland to have 'special EU status' – eg, in the European Economic Area like Norway and Iceland, or, the deluxe model, staying in the Single Market – are shorthand for some necessarily wider UK-EU arrangement. To avoid a hard land border, it has to encompass the customs arrangements not only with 'the rest of the UK', (ie, Britain, with or without Scotland), but also with 'the rest of the (continental) EU', and with 'the rest of the world'. It has to involve all the island's borders, and being an island helps.

A hybrid solution with shared management

This could safeguard all-island free trade, the South's crucial access to markets in Britain, and the North's to continental markets. Ireland could go from potentially suffering most from Brexit to being comparatively advantaged. It could simultaneously be in a free-trade zone with Britain, and in one with the continental EU. These larger zones would overlap in Ireland but would otherwise be completely separated from each other by the hard borders which Britain and the continental EU want for themselves. In effect the island would be an 'intermediate' space located within the hard borders separating Britain from the EU.

Princeton Professor Philip Pettit has detailed a 'shared-space' model of how the entry and exit customs regulations might work. These are always complicated, especially for people and goods which originate 'elsewhere', but to summarise his main points: regulations stay the same as at present for the entry of people and goods to the island from the continental EU and from Britain; exit to the continent and Britain would also follow the existing rules of free movement for people and goods originating in Ireland; but not for those originating outside Ireland. For example, non-Irish EU citizens travelling from Ireland can be denied entry to Britain; and non-Irish goods – for example, cheap US hormone-saturated beef imported into the UK, which contravenes EU health standards – can be denied entry to the continent.

This model's great strength is that much remains the same, but this is also a weakness. Pettit sees the customs authorities in the North and the South mostly operating as presently for things entering and exiting their part of the island, but there is no acknowledgement that their 'shared-space' needs shared or joint management (even if it annoys unionism's right-wing nationalistic fringe). And Ireland already has the basic institutional infrastructures (eg, a North-South Ministerial Council and a British-Irish Council) for shared management democratically accountable to both political jurisdictions, North and South. This is absolutely essential, especially as trade patterns will change in new and threatening ways and Ireland's border management must be able to respond. Take the dreaded US hormoned-beef: Britain might import it, but both electorates might want to stop it entering Ireland.

Smart politics?

The reasons for avoiding a hard land border are compelling and solutions are available, but popular pressure is needed. The EU may not owe Britain any favours but it certainly owes the vulnerable Irish Republic, 'EU loyal' to a fault. Northern Ireland, likewise vulnerable, will have a major concentration of EU/Irish citizens living outside the EU who can demand to be heard. If the EU is politically smart – always a question – it will reward its supporters (including Scotland where 62% opposed Brexit, though its situation is very different from Ireland's).

And if Irish nationalists are smart – sometimes another big 'if' – they will not confuse the challenge of stopping a hard land border with the perennial demand for a 'border poll' on politically re-uniting Ireland. A reckless Brexit might ultimately lead to that, maybe even to a federal Ireland in a confederation with Scotland and both in the EU. But this is to run far ahead of reality. Arguably a border poll will not produce majorities for a united Ireland, especially in the present uncertainties of Brexit. It's a divisive distraction from the immediate task of stopping a hard border. That needs the active support of at least a minority of unionists along with nationalists and others.