This is a very good and fair-minded explainer on the Irish border from @pmdfoster telegraph.co.uk/politics/0/bre… but I’d quibble with one point.
This paragraph is not quite right. Rules are not handed to Dublin (or London) by the EU. The Irish and UK governments and the MEPs their voters elect are the ones who pass the rules. The problem with Northern Ireland is the UK is giving up its say.

That means that voters in Northern Ireland will have no say in the rules governing them, unlike voters in the rest of Ireland. Realistically, the UK will probably have to stay close to EU rules if it wants a decent trade deal of any sort, but at least in return for giving up its
voice in Europe, the Westminster parliament will have sovereignty to the very limited extent of choosing to be a US rule taker or an EU rule taker. Brexit means – against its democratic will – Northern Ireland doesn’t even get the comfort blanket of fake sovereignty.
Originally posted as a thread of 4 tweets on Twitter on 27 January 2019. View the original thread.