Perfectly serious question that's been troubling me about the Brexit situation. How can the border between the Irish Republic and Northern Ireland be any different than that between the rest of the UK and the rest of the EU? I can't see it. Let's look at people but I think the arguments apply equally to goods. If a person can cross the border from NI to the IR without any kind of passport/visa check then anyone who is in, or can manage to get into, the UK is free to go anywhere in the EU. Unless perhaps a "hard" border is established between the IR and the other EU states which I can't see happening. The same is true in the other direction. Either there are controls at the border or between NI and the rest of the UK and the IR and the rest of the EU. Am I missing something?