The international migration of athletes has become an essential feature of sports competition. These days foreign travel is often the name of the game. The purposes and duration of such migration range from participation in single events to long-term, even permanent relocation involving professional transfers. Each purpose or duration may generate a different body of law and regulations. Varying national visa, residence and other requirements for territorial entry of noncitizens are of course essential. Regional, especially European Union law may also be foundational as it was, for example, in defeating a practice within the EU of transfer payments between clubs in different member states that impeded freedom of movement. Also applicable is international law, notably that of the several institutions within the Olympic Movement insofar as it is one of the very few NGOs vested with international legal personality. Supporting that legal authority or extending beyond it are bilateral treaties of friendship and cooperation. More broadly, international human rights law applies, particularly in reinforcing the rights of athletes to be free of political discrimination against their participation in international competition.