‘“[T]hree correcting words of the legislator and entire libraries are turned into maculature.” Worse still: three additional words and entire libraries may be filled again with learned commentaries.’ It is in these apt terms that Robert Schütze has described the principle of subsidiarity. Since its introduction into the constitutional fabric of European Union (EU) law in 1992, a flurry of scholarly research has focused on the principle of subsidiarity, approaching the subject from multiple perspectives—be it legal theory, law and politics, or law and economics—and contextualizing its meaning in multiple legal and policy areas—from environmental law, to the internal market, from education, to social policy, and now criminal law. This widespread interest for subsidiarity is not surprising: as a core constitutional principle of the EU legal order, subsidiarity stands at the crossroads of questions about EU federalism and separations of powers, functionalism and institutional design, and the ends and means of European integration through law.