Aware of these pitfalls, some advocates of linking trade and labour are shy of calling for tariffs and import bans.

ECONOMIST: How not to enforce labour standards

It appeared that Iranian pistachios would finally enter the U.S. last March when Secretary of State Madeleine Albright lifted 13-year sanctions on them, together with import bans on Persian carpets and caviar.

FORBES: Nutty

What is more, the European Union, for one, bans the import of poultry from countries that use vaccines until a year after they were last used.

ECONOMIST: Animal and human health