Since it came into force in 1995, the Schengen Convention has been a symbol of European integration, a measure which lets travellers pass through borders and airports without so much as a wave of their passports. But it is also the incarnation of one of the Eurosceptics' worst fears: the surrender of national border controls.
Free movement of people has been one of the ideals of European politicians for decades. The first experiment dates back to 1960 when Belgium, the Netherlands and Luxembourg had pioneered the axing of border controls under a cooperation agreement.
Now, five years after Schengen became a reality, it covers citizens of Belgium, France, the Netherlands, Germany, Luxembourg, Portugal, Austria, Italy and Spain. Could the United Kingdom one day sign up? In fact, the Government has embraced part of the Schengen package, which it is on the verge of joining. More than a year ago Jack Straw, the Home Secretary, announced that he wanted to opt into key provisions to help combat illegal immigration and international crime, while maintaining the UK's border controls.
A formal application last autumn has been followed by tortuous negotiations with Spain, which has a territorial claim to Gibraltar and is in a position to veto any deal. At last week's Lisbon summit, the Spanish premier, Jose Maria Aznar, said an agreement has been almost finalised, and officials expected formal resolution by Easter.
This is what one official describes as the "repressive part" of Schengen, the section which deals with police co-operation to tackle vehicle smuggling, illegal immigration and drug trafficking. This is now a big part of the Schengen push, and the EU has developed a European database which co-ordinates information, including the movements of asylum seekers. The so-called Eurodac system allows for the comparison of fingerprints of refugees seeking to settle in Europe.
For the UK to go further and axe its border checks for other EU nationals would be a sizeable political gamble - but one which the European Commission expects the Government to take in the medium term.
Brussels argues that, in the post-Kosovo environment, asylum, organised crime and drug trafficking have become intermingled and operate on an international basis - something one country alone cannot combat. Officials believe that a Europe-wide strategy needs to be adopted to deal with the flow of economic migrants and their exploitation by gangs profiteering from human misery.
A stronger Schengen would, the Commission argues, help deter some bogus asylum-seekers because of the growing number of deals which allow repatriation of illegal immigrants to their countries of origins.
At present, a bogus asylum-seeker who enters the UK through another EU state has to be deported to that country, rather than to his or her place of origin. Deals now being negotiated on an EU-wide basis would allow them to be returned home.
But the symbolism of scrapping border controls in Britain is so great that few believe the UK could take the plunge in the run-up to the next general election. "I would be astonished if Britain did so", said one source yesterday.Reuse content