Countries should be able to decide on protectionistic measures themselves (no third world country can, since that would mean they don't get any first world money anymore, and we'll probably do other things to make their life very hard too)
The problem is that this ruling would work both ways. If first world nations were able to introudce all the protectionist measures they wanted, they could cripple third world economies that are often heavily dependant on exports.
If anything, first world protectionism should be produced, especially with regard to manufactured goods. At present, secondary industries in the third world suffer heavily as a result of such measures, forcing them to stick to primary industry which yields significantly lower profit margins and only requires a very basic level of workface education.