The borderless Schengen zone
Europe's worst migration crisis since World War II was in 2015 and put the EU's flagship Schengen agreement under strain as members reintroduced border controls and built walls.
This story by AFP Brussels correspondent Lachlan Carmichael, written at the height of the crisis, takes a look at the Schengen deal, which French President Emmanuel Macron in 2019 suggested should be overhauled to include stricter controls on the EU's external borders and a common asylum policy for migrants.
BRUSSELS, September 14, 2015 (AFP) - Europe's borderless Schengen system, one of the continent's flagship policies, is being put to the test like never before as Germany, Austria and Slovakia move to reintroduce border controls to slow a record influx of migrants and refugees.
Here are some key facts about the 26-nation, passport-free zone:
- Cornerstone of European integration -
The Schengen area is one of the pillars of the European project, enshrining the fundamental right to free movement.
Twenty-two EU countries, plus non-EU Norway, Switzerland, Iceland and Liechtenstein are part of Schengen.
The six EU countries that do not participate are Britain, Ireland, Bulgaria, Romania, Cyprus and Croatia.
The groundwork for borderless travel was laid in 1985 when European countries signed an agreement in the Luxembourg village of Schengen, but implementation took another 10 years.
The first border checks were abolished in 1995 between seven countries : Belgium, France, Germany, Luxembourg, the Netherlands, Portugal and Spain.
The European Commission says that Europeans make more than 1.25 billion journeys within the Schengen area every year.
- Exceptional measures -
Under Schengen rules, member states may "exceptionally" reinstate controls at borders with fellow members "if there is a serious threat to public policy or internal security."
In such cases, the European Commission, the executive of the 28-nation European Union, the European Parliament and other Schengen countries must be informed.
Germany did so on Sunday and immediately began carrying out passport checks on the border with Austria.
Because the events in Germany were not only exceptional but "unforeseeable," commission officials said, Germany can maintain the passport checks for an initial period of 10 days, then renew them for at least two weeks but for no more than two months.
It was the first time, EU sources said, a Schengen country had ever reintroduced temporary border controls over migratory pressures since Europe's internal borders were opened in 1995.
However, it was the 37th time such temporary checks were put in place since then.
Berlin partially lifted the Schengen pact with its neighbours ahead of a G7 summit last June, in a bid to prevent violent protests.
And in 2008, Austria reinstated border controls to tighten security when it was hosting a European football championship with Switzerland.
As both these events were foreseeable, EU sources said, the measures could be introduced for a maximum of 30 days.
Following Germany's move to reimpose border checks, Austria and Slovakia announced similar measures on Monday, fuelling EU fears that the Schengen system may not withstand the pressure from the worst refugee crisis in Europe since World War II.
German Chancellor Angela Merkel already warned in August that Schengen was under threat if member states could not find a way to fairly share the burden of the migrant crisis.
- Police cooperation -
As part of the Schengen agreement, any person, whatever his or her nationality, may cross the internal borders without undergoing border checks.
However national police forces can check travellers as long as their aim is not one of border control.
Member countries on the external borders, such as Hungary on the frontier of non-EU Serbia, assume responsibility for imposing controls and issuing uniform Schengen visas.
In the absence of internal border checks, the Schengen Information System (SIS) has been set up to allow police forces in member states to share data and preserve internal security, including fighting organised crime and terrorism.
In the spirit of police cooperation for serious cases, officers from one Schengen state can pursue suspects in another.