Illegal immigration affects not only EU member states adjacent, but also those distant from the Mediterranean Sea due to open internal borders and intra-EU onward migration. Member states without a direct influx of illegal immigrants may therefore free-ride on border countries’ enforcement...

Illegal immigration affects not only EU member states at the Mediterranean Sea but also more Northern states due to open internal borders and onward migration. Northern member states may free-ride on border countries’ enforcement efforts, leading to a sub-optimal level of border control. While...