Direct from the G20 summit:
If protectionism stems from domestic political pressure, will international "shame" only increase a politician's payoff to trade closure? A leader (or legislature) gets a lot of political mileage out of protecting their constituency from the big, bad, greedy world. But, that political capital skyrockets when that leader/legislature does so in the face of international pressure to do other wise.
I predict lots of David vs. Goliath analogies in the months to come. Just another reminder that audience costs cut both ways - they can constrain or embolden.