Given that the EU has open borders and markets (for the most part), isn't it a germaine discussion if that supranational entity wants to enlarge its borders to

Given that the EU has open borders and markets (for the most part), isn't it a germaine discussion if that supranational entity wants to enlarge its borders to include ports of entry from a somewhat unstable country? I mean... britain wouldn't be the ones policing the border, it would be turkey. You may be confusing the EU with the Schengen area, which is indeed (relatively) physical border less. While most EU countries are in the Schengen area (including the non-EU members Norway, Iceland, Liechtenstein and Switzerland) the UK was never part of the Schengen accord and manages its own borders. While you're never asked for identification when you fly from Dusseldorf to Zurich, border controls are quite strict (on both sides) if you fly from Prague to Manchester (or to Manila for that matter). Taking back control of the borders was always pretty much a bullshit argument, if not an outright lie by the Brexiteers, since britain never gave that up.