As the world's most exciting sports event begins, I was hoping to conjure up a link to IEL. How about this. National teams are limited to nationals. The team administrators obviously discriminate in the national treatment sense against foreign players. Would this violate a GATS commitment in the relevant sector, assuming for a moment that the players are service providers under Mode 4? The first answer is, "it's not a measure," at least to the extent that the teams are private. But would it be a measure to decline to enforce otherwise applicable national laws against employment discrimination on the basis of nationality? Would it be a measure to carve out an exception to those laws? The second answer is that it does not violate national treatment, or that it is not "less favourable," if there is a a non-protectionist type of reason for the differential treatment.
I don't want to be a spoil-sport (so to speak), but just thought the blog should get it on the World Cup hype. For some international relations-soccer links, see this Council on Foreign Relations site.