W has never had any problems traveling abroad. He might once he's no longer President, and no longer has the immunity from having his collar felt as am accused war criminal.

But then I doubt if he'll risk travelling too much.
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As for the Medellin execution, since it was done in clear breach of international law - as confirmed by Bush's attempt to intervene - this could mean that the Texas Governor concerned might be at risk of being arrested if he ever leaves the USA. Technically, in international legal terms, this execution should count as a lynching.