PRAGUE — It is time for Europe's politicians to admit to voters that governments cannot stop people moving across borders. Despite efforts to build a Fortress Europe, over a million foreigners bypass its defenses every year; some enter covertly, but most just overstay their visas and work illicitly. Even if Europe became a police state, migrants could get through: documents can be forged or stolen, visas overstayed, people smuggled, officials bribed. While Draconian policies can curb migration somewhat, they mostly drive it underground.

That creates huge costs. Aside from a humanitarian crisis, with thousands drowning each year trying to reach Europe and thousands more detained, there is the soaring expense of border controls and bureaucracy, a criminalized people-smuggling industry, and an expanding shadow economy, where illegal migrants are vulnerable to exploitation, labor laws are broken and taxes go unpaid. In addition, there is rising mistrust of politicians who cannot fulfill promises to halt immigration, accompanied by perceptions of immigrants as lawbreakers rather than enterprising people, and mistreatment of refugees aimed at deterring people who want to work from applying for asylum.

These problems are due not to immigrants, but to our immigration controls, which are not only costly and cruel, but also ineffective and counterproductive. Far from protecting us, they undermine law and order, just as Prohibition did more damage to America than drinking ever has. Pragmatic governments surely ought to legalize and regulate migration instead.