Terra nullius (/ˈtɛrə.nʌˈlaɪəs/, plural terrae nullius) is a Latin expression deriving from Roman law meaning "nobody's land", which is used in international law to describe territory which has never been subject to the sovereignty of any state, or over which any prior sovereign has expressly or implicitly relinquished sovereignty. Sovereignty over territory which is terra nullius may be acquired through occupation, (see reception statute) though in some cases doing so would violate an international law or treaty. Terra nullius is derived from the 1095 papal bull, Terra Nullius, of Pope Urban II, which allowed Christian European states to claim land inhabited by non-Christians.