Regulations relating to the eligibility of players to play for national teams in rugby union, both in the fifteen-a-side game and rugby sevens, are the responsibility of World Rugby, the governing body for the sport. Players' eligibility to represent a country depends on whether they have a genuine, close, credible and established national link with that country.[1]
In principle, as soon as a player has represented a country internationally (has been "captured" by that country), they are no longer permitted to represent another country. However, a player is allowed to transfer to another country once, with approval of the World Rugby Regulations Committee, if the player is born in the country to which they wish to transfer or has a parent or grandparent who was born in that country. Playing for a second country is not permitted by means of residency. Switching countries is also possible through playing in Olympic events, provided the player has the nationality of the second country. In any case, a stand-down period of three years applies.