Since the pan-Arab uprising began in January in Tunisia, Italy has been sounding the alarm bell about an increase in migrants trying to cross the Mediterranean to escape the chaos in North Africa. The tiny Italian island of Lampedusa, just off the Tunisian coast, has been inundated with refugees washing up on its shores in makeshift boats. There are now more migrants housed in a refugee camp on the island than there are residents.

Italy has asked the EU for assistance in dealing with the migrants, most specifically through deployment of the EU's Frontex border patrol force. They have also asked other member states to contribute financially to the effort, saying that Italy can't afford to patrol the EU's borders all on its own. Because the Schengen Zone is a passport-free area, most of the migrants crossing into Italy are just trying to get into the EU. Once they get into Italy they can go to France, Sweden or Germany without facing a border check.

Italy thinks that the other member states have not responded quickly enough to their pleas for assistance, particularly France. So in the past weeks the Italian government has taken the unusual measure of issuing 'temporary residence permits' to the mostly French-speaking migrants, putting them on trains to France and telling them they should go there to look for French-speaking jobs. This has enraged France, which says the issuance of such temporary IDs is a violation of the EU's Schengen rules. The migrants can only come into France if they've been issued Schengen work visas, they say.

In retaliation, France began stopping trains they suspect of containing the migrants, holding them for hours and asking each passenger for identification. This is, on its surface, a rather obvious violation of Schengen rules, which stipulate that member states cannot conduct checks at the zone's internal borders. Italy has said it will launch a formal complaint to the EU about the violation.

But in fact, what France is doing may actually be legal through a loophole in the law. Article 21 of the Schengen agreement says that police (not immigration officials) may conduct checks of identity documents near (but not at) the border, but these cannot be the "equivalent of border controls" and they can only be done in response to a "threat to public security". Alternatively, member states can re-establish border checks at internal Schengen borders for limited periods of 30 days in response to a serious foreseeable threat.

It is not clear which of these legal justifications France is using because there are conflicting accounts about whether it was police or immigration officials who stopped the trains. But based on what a spokesperson for the European Commission told journalists today, either way it looks like France could justify the checks because member states are the ones who determine what is a "threat to public security" or a "serious foreseeable threat". So if France says that Italy dumping migrants into France constitutes a serious threat to public safety, the commission apparently can't do anything about it. From the sounds of it, France could theoretically re-establish complete border checks at its Italian border simply be perpetually renewing these 30 day emergency periods and saying that a serious threat continues to exist.

Of course, this would be a gross violation of the spirit of the law. The 30 day emergency re-establishment of border checks has only ever been used three times before – once by Portugal during the European Football Championship, once by Spain during the wedding of Crown Prince Felipe and once by France during the ceremonies marking the 60th anniversary of D-Day. All three of these instances were for an anticipated influx of people crossing an internal Schengen border for a large event. If France is now using the emergency clause for an ongoing problem that will seemingly never cease (illegal immigration), it would be a huge departure from how it has been used in the past. And it would suggest that in actuality any member state can re-open its immigration facilities at internal Schengen borders if it so chooses, as long is it cites a vague threat to public security.

When asked how the Schengen rules can be seemingly so loose, the commission spokesperson said today simply, "Schengen is a trust-based system." If that is the case, then the Schengen Zone is in deep trouble because trust is something that is in short supply in Europe these days.

Italy doesn't trust the rest of the EU to help it deal with an influx of migrants, so it unilaterally invents a new type of ID for them and sends them to other countries. But Italy has done this in a way which hasn't engendered much trust from either France or the commission. The Italian interior minister told Italy's Sky TG24 TV over the weekend, "We have given the migrants travel documents, and we gave everything that is needed, and the European Commission recognised that, it has said that Italy is following the Schengen rules." But not only did the commission insist today that a 'temporary resident permit' is not a valid travel document, they also said they never gave any such endorsement to the Italian actions and have not yet been officially notified by Italy about the ID plan. This is the second time the Italian government has appeared to misrepresent its conversations with the commission recently. In February the foreign minister claimed the country had officially asked the commission for asssitance with the migrants when, according to the commision, it had not yet done so.

For its part France setting up these impromptu border checks sends a message that it clearly doesn't trust Italy to carry out the EU's external border checks. France and Germany have also suggested that they don't trust Greece to patrol the EU external border with Turkey. This trust is, as the commission said, at the very heart of the Schengen system. If France can set up border checks by declaring that a "threat to public security" is being created by Italy's misapplication of the Schengen rules, then what's to stop every member state from doing the same? Before we know it the Schengen Zone could degenerate into a series of limited passport-free zones existing only between countries that trust one another. We could see one zone for Eastern Europe, one for Northern Europe, and one for Southern Europe, with checks set up along the Latin-Germanic divide and along the former iron curtain on the basis of "threats to public security".

The current confusion shows that the Schengen rules are not as airtight as it may have seemed. Just a few months ago the commission announced it was going to crack down on member states who aren't abiding by the Schengen zone rules. Perhaps they should first check if those Schengen zone rules are even enforceable.