Since the British referendum to leave the EU I often hear that Brexit threatens the Good Friday Agreement. As far as I know the Good Friday Agreement pretty much ended violent conflict in Northern Ireland after 1998. The most important points of the agreement that I could find are:

  • The Irish Government refrains from reunification of the island
  • Reunification is still possible if a majority of Northern Irish agree
  • Paramilitary groups agree to disarmament
  • Northern Irish can have dual Citizenship
  • Cooperation between British and Irish governments
  • Retraction of the Government of Ireland Act

These points are mainly from here.

As far as I can tell none of these points depend on the status of the United Kingdom as a member of the European Union. Why then does Brexit threaten the Good Friday Agreement?


1 Answer 1


A key aspect of the GFA was the removal of all border apparatus on the Island of Ireland. The border was often a target of violence and a physical divider between the two communities.

If the UK leaves the EU Customs Union then products which do not meet EU standards will be able to enter the UK and cross the border into Ireland. Similarly people, livestock and vehicles could cross.

The normal way to prevent this is to have border controls, which were abolished by the GFA. The EU has therefore requested that if the UK wishes to leave the Customs Union it must find a solution to this problem that does not involve any infrastructure on the border itself. If the UK does not then the EU is unwilling to allow negotiations on other issues to proceed.

Some of the more extreme Brexit supporters have suggested that the UK should simply leave without a deal and simply leave the border open on its side, forcing the EU to either do the same or be responsible for installing checks. That idea is widely considered impractical, not least because it would realistically prevent the UK entering customs unions with other non-EU nations as it had no control over its largest land border.

  • 2
    Have you read the GFA? It does not actually mention border controls at all. Also, the lack of a customs union concerns more than just product standards; the lack of a unified tariff system is enough to require customs controls. I'm also unaware of any discussion of the UK entering a customs union with any other nation. Free-trade agreements, yes, but a free-trade agreement is not remotely the same thing as a customs union.
    – phoog
    Commented Nov 16, 2018 at 15:51
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    @phoog In general talking heads saying "threatens the Good Friday/Belfast Agreement" should probably read as "threatens the civil stability maintained following the implementation of the Good Friday/Belfast Agreement".
    – origimbo
    Commented Nov 16, 2018 at 16:32
  • 1
    @origimbo that's perfectly reasonable; the problem is that people seem to think that the agreement directly abolished border controls when it in fact says nothing about border controls whatsoever. The relationship between the agreement and the border controls is therefore rather more complicated. Customs controls were abolished in 1993, after which border checkpoints were presumably for security only. The reintroduction of customs controls does not necessarily imply a threat to security or civil stability, but the added friction could indeed threaten them.
    – phoog
    Commented Nov 16, 2018 at 17:06
  • The UK is not rumored to be considering customs unions and with any other countries.
    – phoog
    Commented Sep 1, 2019 at 5:32
  • Does the UK have more than one land border? Commented Dec 29, 2020 at 21:06

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