Throughout the sham Brexit negotiations the issue of the Northern Irish border has been the main focus with the hated “backstop” proving to be a particular sticking point. But in actual fact it is not the UK/Irish border that is the problem, it’s the EU/Irish border that is.
The idea that the border between Ireland and the UK should remain open and largely uncontrolled for both people and goods is perfectly sensible. Ireland is a large market for the UK, the UK’s only land border is with Ireland, there are lots of cross-border communities and of course the UK is Ireland’s largest trading partner. We’ve had a common travel area covering the whole of the British Isles since 1923 and it was updated as recently as 2014 to allow Indian and Chinese nationals to travel throughout the British Isles on a single visa.
To make a common travel area work the participating states need to be in control of their borders and trade policy. Each participating state relies on the others to apply a common level of control over their borders so that only people and goods permitted to move between them are able to do so. You can travel between the UK and Ireland by sea without a passport if you are a UK or Irish citizen because the Irish government trusts the UK to ensure only British and Irish citizens are allowed onto ferries without a passport and vice versa. Travel across the land border between the UK and Ireland is uncontrolled because there are adequate controls in place at our external frontiers.
The common travel area can remain in place after Brexit as long as every participating state can continue to control its external frontier and carry out adequate customs duties. Outside of the EU the UK can control its borders. We can ensure that the only people and goods entering the UK and subsequently travelling from the UK to Ireland are authorised to do so. Ireland, on the other hand, will have to allow all EU or EEA citizens and goods enter the country whence they will be able to travel into the UK whether authorised or not.
The problem is therefore with Ireland and its inability to control its border with the EU. The Irish can either have free movement of people and goods with the EU or with the UK, they can’t have both. While the EU sets Ireland’s trade tariffs and controls its borders they will be unable to facilitate free movement of people and goods with the UK. This is a decision for the Irish to make, it is not the UK’s problem to solve.
Ireland needs a backstop agreement with the EU, not the UK.