Identification is not legally necessary for domestic journeys within the United Kingdom.

Take the following three-legged journey:

  1. Fly from a non-EU country to Dublin
  2. Ride a coach to Belfast
  3. Sail a ferry to Liverpool

In this journey I go through passport control in the Republic of Ireland but not in the United Kingdom.

A carrier might demand such documentation for their own purposes but I will ignore this aspect here.

Does this mean that because of the Common Travel Area, and ignoring intelligence-led interdiction, a portion of UK border control is delegated to the Republic of Ireland?

  • 4
    The answer really depends on what you mean by "border control" and by "delegate." As you note, it is possible to reach UK territory having been inspected only by Irish border officers. To my mind, that fact by itself means that the answer to your question is "yes." But since you note that fact in asking the question, I suspect that you're looking for something else. Are you?
    – phoog
    Jun 11, 2019 at 16:00
  • Your first interpretation of the question was what I was looking for. Given this, I have a supplementary: what implications does this have for the border of the Republic of Ireland (if any).
    – 52d6c6af
    Jun 11, 2019 at 16:09
  • 2
    There's a system called Timatic that is a database for passenger requirements. I believe this to be valid in most countries (EU or not). So if an airline let's you travel without a VISA for your destination they will probably need to bring you back at their own cost. In your example the passenger would be checked in the non-EU country and then in Ireland. This would be the last check because, as the UK, Ireland is not in the Schengen agreement (important to maintain an open border with Northern Ireland).
    – armatita
    Jun 11, 2019 at 16:09
  • 2
    @Ben yes. If the UK wanted to join Schengen, Ireland would have done so.
    – phoog
    Jun 11, 2019 at 16:17
  • 1
    It’s not actually possible to get from Belfast to Liverpool without some form of ID check. I am not sure what responsibilities the uk govt has given the ferry companies when they do the ID check however.
    – Simd
    Jun 12, 2019 at 4:51

1 Answer 1


The UK and the Republic of Ireland have maintained the common travel area for nearly a century through a series of non-binding agreements. The most recent agreement, in 2011, was the first public one. It does not contain an explicit delegation of border authority, but makes it clear that the parties understand that they share responsibility for the common external border. For example:


  1. Ireland’s Department for Justice and Equality and the United Kingdom’s Home Department in recognition of the protection of the Common Travel Area (CTA) arrangements, as a legitimate and fundamental public policy for both the Irish and United Kingdom Governments, have committed to a joint programme of work on measures to increase the security of the external Common Travel Area border.

Another example:

  1. e-Borders/Irish Border Information System (IBIS)

    The two governments understand that the overall aim through working together in the development of e-Borders/IBIS is to develop an electronic border management system/s to identify, as early as possible, those persons who have no right to enter the CTA or who would seek to cause harm, so that appropriate action can be taken to deal with them at the earliest possible juncture. Both governments are committed to the development of such electronic border management systems, building on the experience gained by the UK in rolling out their e-Borders system, and will continue to explore all possibilities to make this happen.

You could call this delegation of responsibility or sharing responsibility. Either way, it is mutual, for just as it is possible to enter the UK having been inspected only by an officer of the Republic of Ireland, it is also possible to enter the Republic of Ireland having been inspected only by an officer of the UK.

  • And thus making a hard Brexit nearly impossible, because Ireland is a member of the EU.
    – nick012000
    Jun 13, 2019 at 5:12
  • 2
    @nick012000 the CTA has nothing to do with the difficulties of hard Brexit, since both Ireland and the UK are outside the Schengen area. The countries have different visa policies already, have never had routine immigration controls on the border, and will have no need to introduce them after Brexit. The difficulties arise from the customs union.
    – phoog
    Jun 13, 2019 at 5:47

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