 One way to address this mismatch is to reconsider how entitlement to citizenship is determined. In a world characterized by significant levels of migration across states, birthright citizenship — acquired either through descent (jus sanguinis) or birth in the territory (jus soli) — may lead to counterintuitive results: while a regime of pure jus sanguinis systematically excludes immigrants and their children, though the latter may be born and bred in their parents’ new home, it includes descendents of expatriates who may never have set foot in their forebears’ homeland. On the other hand, a regime of jus soli may attribute citizenship to children whose birth in the territory is accidental while denying it to those children who have arrived in the country at a very young age.