![](https://www.cer.eu/sites/default/files/styles/spotlight/public/brexit_question_sl_11.jpg?itok=BDJzz_So)
The EU is Northern Ireland's biggest trading partner
As the Centre for European Reform explains, and I quote: "In order to maintain access to EU markets, a Britain on the outside would have to sign up to many of the EU's rules. As a non-participant in the EU’s institutions, it would have little say over the rules."