It sounded like a historical moment was in the offing. For the first time, Europe’s finance ministers were seriously planning on publicly denouncing tax havens by presenting a black list of countries that lure companies through tax-saving schemes. French Finance Minister Bruno Le Maire said the countries on the list were “not doing enough to fight tax evasion.” Fellow Frenchman Pierre Moscovici, the European Union’s commissioner for economic and monetary affairs, called for vigorous sanctions. […] That was one and a half years ago, and that momentum has largely disappeared. This is partly because the black list had several fundamental...