From an FT article:
Fredrik Erixon, of the European Centre for International Political Economy, a free-market think-tank in Brussels, says: “WTO rules are effective where you have one country behaving badly. Where there is a protectionist power balance between all the big countries, they aren’t of much use.”
I don't know. There is a lot of protectionism allowed under WTO rules. One could argue that "protectionist power balance between all the big countries" is a pretty good description of the GATT/WTO in general.