The European elections, which wrapped up this past weekend, are a grim warning that should be raising alarms and hackles the world over. Without a doubt, the biggest beneficiaries of this election have been a cadre of mostly right-wing, anti-EU parties united by strident anti-immigrant policies and over-the-top rhetoric that has made enemies of everyone from Muslims to Romanians.

Why should we be concerned about this on this side of the pond? Because much of this political rhetoric is simply localized variants on themes that bedevil us in the U.S. as well, and ...