What about Corbyn’s plan to place the UK in
a permanent customs union with the EU? This would certainly eliminate the need for customs controls to collect tariffs – as a customs union would eliminate tariffs on all goods crossing internal frontiers. But it would not eliminate customs controls entirely. This can be seen from the fact that between 1973 and 1992, the UK and Ireland were in a Corbyn-style customs union with each other (called the European Economic Community) and
yet customs controls were maintained.
Member states of a customs union can maintain all sorts of regulations – such as health standards, agricultural controls and minimum product standards – and goods entering the market need to be checked for compliance with these. This is exactly what customs officers along the Northern Irish border were doing until the single market emerged in 1993.
Only in a single market are such standards harmonised or mutually recognised on a comprehensive basis – without the need for customs checks. This is why it was possible to abolish systematic customs checks along the border in 1993.
Corbyn’s proposal, if the EU agreed to it, would reduce customs checks along the frontier and be a hugely welcome boost to cross-border trade and to the prosperity of both the UK and Ireland. It is also infinitely preferable to the May-Johnson free trade area plan. What it will not do, however, is end the prospect of a hard border.
For this, both Northern Ireland and the Republic of Ireland need to be in a single market with one another. One way of doing this is for the UK as a whole, in leaving the EU, to stay in a single market and customs union relationship with the EU 27 states – what could be called a “Norway plus” deal. Another is the fall-back option within the EU’s draft withdrawal agreement – that Northern Ireland remains part of the current EU customs territory after Brexit.