In policing its borders as late as 2016, the E.U. suffered the same plight as the U.S. did under its Articles of Confederation—only whereas in the case of the U.S. the States retained all of their governmental sovereignty under the Articles, some governmental sovereignty in the E.U. was already lodged at the federal level. I contend that this perplexing disjunction between extant federal competencies and state rights in the E.U. is not sustainable.
The full essay is at "E.U.'s Border-Control."