Huge amounts of time, effort, and frustration have gone into negotiating the terms of the UK’s exit from the European Union. And with the UK set to hold a crucial parliamentary election on December 12, it still is not clear whether, when, and how Brexit will happen.

But assuming the UK does leave the EU, its next government will need to begin the long, difficult process of negotiating new relationships with the rest of the world. That will involve tough choices, one of the thorniest of which is whether the UK should align its regulations in key economic sectors with those of the EU or the US.