Migrants and refugees flooding into Europe have presented European leaders and policymakers with their greatest challenge since the debt crisis. The International Organization for Migration calls Europe the most dangerous destination for irregular migration in the world, and the Mediterranean the world’s most dangerous border crossing.

Distinguishing migrants from asylum seekers and refugees is not always a clear-cut process, yet it is a crucial designation because these groups are entitled to different levels of assistance and protection under international law.

“Both the burden and the sharing are in the eye of the beholder. I don’t know if any EU country will ever find the equity that is being sought”

Migrant detention centers across the continent, including in France, Greece, and Italy have all invited charges of abuse and neglect over the years. Many rights groups contend that a number of these detention centers violate Article III (PDF) of the European Convention on Human Rights, which prohibits inhuman or degrading treatment.

In contrast, migrants in the richer north and west find comparatively well-run asylum centers and generous resettlement policies. But these harder-to-reach countries often cater to migrants who have the wherewithal to navigate entry-point states with safe air passage with the assistance of smugglers.

These countries still remain inaccessible to many migrants seeking international protection. As with the sovereign debt crisis, national interests have consistently trumped a common European response to this migrant influx.

Some experts say the bloc’s increasingly polarized political climate, in which many nationalist, anti-immigrant parties are gaining traction, is partially to blame for the muted humanitarian response from some states. France and Denmark have also cited security concerns as justification for their reluctance in accepting migrants from the Middle East and North Africa, particularly in the wake of the Paris and Copenhagen terrorist shootings in early 2015.

“The backdrop is the difficulty that many European countries have in integrating minorities into the social mainstream”

Underscoring this point, leaders of eastern European states like Hungary, Poland, Slovakia, and the Czech Republic have all recently expressed a strong preference for non-Muslim migrants. In August 2015, Slovakia announced that it would only accept Christian refugees from Syria. While selecting migrants based on religion is in clear violation of the EU’s non-discrimination laws, these leaders have defended their policies by pointing to their own constituencies’ discomfort with growing Muslim communities.

The recent economic crisis has also spurred a demographic shift across the continent, with citizens of crisis-hit member states migrating to the north and west in record numbers in search of work. Some experts say Germany and Sweden’s open immigration policies also make economic sense, given Europe’s demographic trajectory (PDF) of declining birth rates and ageing populations. Migrants, they argue, could boost Europe’s economies as workers, taxpayers, and consumers, and help shore up its famed social safety nets.

In August 2015, Germany announced that it was suspending Dublin for Syrian asylum seekers, which effectively stopped deportations of Syrians back to their European country of entry. This move by the bloc’s largest and wealthiest member country was seen as an important gesture of solidarity with entry-point states. However, German Chancellor Angela Merkel also warned that the future of Schengen was at risk unless all EU member states did their part to find a more equitable distribution of migrants.

Germany reinstated temporary border controls along its border with Austria in September 2015, after receiving an estimated forty thousand migrants over one weekend. Implemented on the eve of an emergency migration summit, this move was seen by many experts as a signal to other member states about the pressing need for an EU-wide quota system. Austria, the Netherlands, and Slovakia soon followed with their own border controls. These developments have been called the greatest blow to Schengen in its twenty-year existence.

In September 2015, the European Commission President Jean-Claude Juncker announced plans to revisit a migrant quota system for the bloc’s twenty-two participating members. Juncker’s second attempt to institute a quota.