Mercosur has not managed to keep a common front in trade talks with outsiders, as a customs union is supposed to do.

ECONOMIST: Another blow to Mercosur

This authority supersedes common readings of the Constitution, the law and the customs of governance in America.

NPR: Justifications More Troubling Than Spying Itself

The disarray of the customs union has gone hand-in-hand with a lack of progress in deepening Mercosur by achieving common policies towards trade among members.

ECONOMIST: Another blow to Mercosur