Borders between the European Union’s 27 member states are supposed to be free of passport checks, but during the 2015 migrant crisis a number of countries set up controls to stem the flow of millions fleeing the Syrian civil war.

Borders between the European Union’s 27 member states are supposed to be free of passport checks, but during the 2015 migrant crisis a number of countries set up controls to stem the flow of millions fleeing the Syrian civil war.