In 2017, McAleese described Brexit as like "pulling a tooth with 10,000 roots". She said that Northern Ireland will be the only part of the UK that will share a land border with an EU state post-Brexit and she feared that checks between Northern Ireland and the Republic of Ireland would be an inevitable consequence of the UK leaving EU. McAleese said "the lawyer in me says our migration controls are very different, and they are going to be if Britain is no longer part of the EU, and if they tighten the migration controls it won't be enough that I'm entitled to use the Common Travel Area…how are they going to differentiate between me, the person who is entitled to plead the Common Travel Areas, and the person say from France or Germany or Poland who's going to cross the road at Newry, or Derry? My view is that sooner or later the pressure will come to make it an ID card phenomenon…I don't see, in the long run, how we'd get around that".Taoiseach Leo Varadkar responded to McAleese's concerns saying "I understand her concerns but it is one area that I am very sure about that's that there won't be a requirement to produce a passport to travel to Northern Ireland".