Unclaimed territory, formally correct terra nullius, is a word from International law. It is used to talk about land which has never been under the rule of any state. It can also be that the previous owner has given up their ownership. This can be done either implicitly or explicitly. There is also the term No man's land, but it may have a slightly different meaning. Rule over terra nullius can be obtained by occupying the territory.
- "New Jersey v. New York, 523 US 767 (1998)". US Supreme Court. 26 May 1998. Retrieved 29 January 2010.
Even as to terra nullius, like a volcanic island or territory abandoned by its former sovereign, a claimant by right as against all others has more to do than planting a flag or rearing a monument. Since the 19th century the most generous settled view has been that discovery accompanied by symbolic acts give no more than "an inchoate title, an option, as against other states, to consolidate the first steps by proceeding to effective occupation within a reasonable time.8 I. Brownlie, Principles of Public International Law 146 (4th ed.1990); see also 1 C. Hyde, International Law 329 (rev.2d ed.1945); 1 L. Oppenheim International Law §§222-223, pp. 439-441 (H. Lauterpacht 5th ed.1937); Hall A Treatise on International Law, at 102-103; 1 J. Moore, International Law 258 (1906); R. Phillimore, International Law 273 (2d ed. 1871); E. Vattel, Law of Nations, §208, p. 99 (J. Chitty 6th Am. ed. 1844).