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Schengen is a small village in Luxembourg where in 1985 the first agreement was made among EU countries to abolish border controls at their common borders. It gave its name to the Schengen area, consisting of the countries that apply these rules, which came into effect with eight states in 1995.

The area has since grown: In addition to 22 EU member states, it includes Switzerland, Liechtenstein, Norway and Iceland. Great Britain and Ireland have not fully joined and maintain external border controls but take part in some Schengen-related exchanges of information. Cyprus, Romania and Bulgaria are waiting in the queue. Cyprus cannot join because its north is occupied by Turkey. And in the opinion of some countries that are already in the Schengen zone, including Germany, Romania and Bulgaria do not fulfill the conditions necessary to do away with border controls with their EU neighbors.

The most important demands made of members are the ability of the Schengen countries to secure their borders to non-EU countries, to stop illegal entry and prevent crime. The EU Commission has recognized Bulgaria and Romania's ability to do so after a transition period of several years. Germany and the Netherlands are skeptical and have postponed the abolition of border controls with the two southeastern European countries several times.

Bulgaria and Romania are already in the "Schengen area"

Complicating the issue in a way only the EU can, Romania and Bulgaria have already legally entered the Schengen area by joining the European Union in 2007. The original rules of the old Schengen agreements have become key elements of EU treaties and cornerstones of the internal market and free movement within the bloc.

Romania and Bulgaria have agreed to bringing asylum and visa policies in line with EU rules, increasing checks along their borders with non-EU countries, fighting drug-related crime, and the preventing smuggling and trafficking. They are also part of the "Schengen Information System" (SIS), which provides police authorities in the EU with quick access to data on entries and exits. Another system for the electronic acquisition of data on visas and illegal entry and exit of persons in the Schengen area is in preparation.

The only rule that Bulgaria and Romania cannot yet apply is the abolition of checks at the border, which remains the most visible aspect of the Schengen agreement.

Freedom has its exceptions

Today, the free movement of persons within the "Schengen area" for EU citizens has largely been achieved. In exceptional circumstances, for example during major international events, checks at internal borders can be temporarily reintroduced. This happened for example during soccer's European Championships and World Cup, and in advance of the Group of Eight and NATO summits.

Several EU countries, led by France and Germany, in June 2012 brought back border checks if an EU state allows too many refugees to enter the Schengen area. Before doing so, however, it must determine that a threat to public safety exists. Crisis-ridden Greece is considered by many EU interior ministers not to be in a position to safeguard its external border with Turkey sufficiently. Some in the EU fear Bulgaria and Romania could turn into transit countries for illegal entries from Ukraine and the Western Balkans to the rest of the union if border checks are abolished. After all, once in the Schengen area, no one is held back by any further internal frontier.

The attempt of Denmark to permanently reinstall customs controls at its borders was abandoned in 2011 after a few months. Issuing visas for the "Schengen area" is also part of the asylum process in the European Union. Refugees and asylum seekers, however, usually receive only residence permits - not visas - for the country of entry and are seldom permitted to move freely within the Schengen zone.

Romanians and Bulgarians can already travel freely

It is wrong to conflate the Schengen issue with the situation of the Romanians who are currently immigrating to Germany in increasing numbers, said Franziska Keller, a member of European Parliament for the Greens. In Brussels, she said Roma who are Romanian citizens could already travel in the EU as well as establish residency in many countries. The controls at the Romanian borders with EU countries are not an obstacle.

In contrast, German Interior Minister Hans-Peter Friedrich told "Der Spiegel" news magazine, "Those who come only to collect benefits, and abused the freedom of movement, must be effectively prevented."

But such presumed abuse can scarcely be prevented by maintaining checks on persons at internal borders, because EU citizens have freedom of movement. In light of this, Friedrich is, therefore, calling for Roma who have already been deported from Germany to be denied re-entry. That would be a greater restriction of the freedom of movement and the Schengen rules. As part of a deal agreed with the countries in 2007, after the end of a transitional period ending in 2013, Romanians and Bulgarians may freely settle permanently in Germany and other EU countries, as long as they have work or are in enrolled in a course of study. That was agreed with the accession of the two countries in 2007.

It is only possible to visit any of the countries of the Schengen area from most parts of Africa and Asia with a special visa. The visa requirement also applies to Russia and Turkey. North Americans, most South Americans, Australians and Japanese are admitted without a visa for three months. Citizens of the Western Balkan countries can also enter without a visa to the EU, with the exception of citizens of Kosovo, which is not recognized by all EU countries.