The question that kept Europe on the existential edge of its seat earlier this year asked whether Greece's economic dysfunction was so severe it should be ejected from the Euro Zone, the select group of European Union countries that share a common currency.
But the ongoing torrent of immigrants washing over Europe, and Germany's announcement Sunday it was reimposing border controls because of them, raise equally troubling questions about Greece's membership in another exclusive club, the Schengen Zone, where border checks between its 26 members no longer exist.
Has Greece, the easternmost portal to a borderless Europe, done its job to protect the continent's southeastern flank? And if not, should it be kicked out of the Schengen Zone before Europe's historic experiment with seamless internal travel collapses?
These weren't questions the leaders of Germany, France and the Benelux countries (Belgium, Luxembourg and the Netherlands) envisioned in 1985 when they gathered in the Luxembourg village of Schengen to begin tearing down the border checkpoints between them.
They were thinking about speeding the construction of an open and unified European Union, as well as eliminating border congestion and lowering transportation costs in what became known as the Schengen Zone.
Over the years, more EU members signed on, and the idea grew so popular that even a few non-EU countries joined. But not all countries qualified. Romania and Bulgaria, two relatively recent EU members, have been trying to enter the border-free zone for several years, but have been unable to convince the current Schengen members they could block unauthorized immigration across their boundaries from non-Schengen countries to the east.
Ironically, this is the very problem that now plagues Greece, which joined the Schengen Zone in 1992.
Schengen rules effectively eliminate all border controls between its members, although they allow a country to temporarily reinstate checks for security reasons, as France, Denmark and Italy have done in the past, and Germany, Hungary, Austria and the Netherlands are doing now. But unrestricted internal travel comes at a price - Schengen countries have to do their part to secure the zone's 30,000 miles of external borders, which includes more than 26,000 miles of seacoast. Because once you are in the zone, it is the functional equivalent of travelling within the United States.
For the last several years those external borders have been under siege. Unauthorized immigrants from Africa have gambled their lives to reach the nearby coasts of Italy or Spain, where they either apply for asylum or take advantage of open borders to move on to other Schengen countries.
Greece, which shares the only land border among the Schengen members with the Middle East, a 126-mile land border with Turkey, has been the second most favored route, especially for those streaming west from Syria and Afghanistan. Over the last six months, that stream has become a flood. And given its precarious finances and the steady erosion of government services due to mandated spending cuts, Greece has been less and less capable of staunching the flow.
Kicking Greece out of Schengen could be difficult. No mechanism exists for ejecting a member -- indeed, all new EU members are required to join after they prove they can live up to Schengen's requirements. It would also be unfair.
Greece is just the poster child for an open-border system that suffers from a major weakness. Because while the consequences of a porous external border affect all Schengen members, the burden of actually patrolling it falls to the individual states on the periphery, like Greece. In extremis, these states can call on centrally funded Schengen institutions for assistance.
One of those institutions is an agency called Frontex, which superficially resembles the U.S. Border Patrol. But Frontex is more of a coordinating body than an action agency, and it depends on contributions of agents and equipment from the Schengen countries to do its work. Its 2014 budget of roughly $110 million paid for a staff of 317; the U.S. Border Patrol, by contrast, counts more than 20,000 agents. Frontex recently offered to double the number of inspectors assisting Greek officials on the island of Lesbos, where nearly 50,000 migrants landed in July alone. But that doubling would bring the size of its contingent there to only 20 officers.
Strengthening Schengen's external boundary will revive charges that the EU is creating a Fortress Europe. But if European leaders want to save their vision of open borders, a model that could be attractive here in North America if Mexico could gain better control over its southern border, they have to get serious about regulating their external border, or accept the return of internal border checks.
That would be a loss for them, and for us.