information:highlighting
External

External sovereignty concerns the relationship between sovereign power and other states. For example, the United Kingdom uses the following criterion when deciding under what conditions other states recognise a political entity as having sovereignty over some territory;

"Sovereignty." A government which exercises de facto administrative control over a country and is not subordinate to any other government in that country or a foreign sovereign state.

(The Arantzazu Mendi, A.C. 256), Stroud's Judicial Dictionary

External sovereignty is connected with questions of international law – such as when, if ever, is intervention by one country into another's territory permissible?

Following the Thirty Years' War, a European religious conflict that embroiled much of the continent, the Peace of Westphalia in 1648 established the notion of territorial sovereignty as a norm of noninterference in the affairs of other states, so-called Westphalian sovereignty, even though the treaty itself reaffirmed the multiple levels of the sovereignty of the Holy Roman Empire. This resulted as a natural extension of the older principle of cuius regio, eius religio (Whose realm, his religion), leaving the Roman Catholic Church with little ability to interfere with the internal affairs of many European states. It is a myth, however, that the Treaties of Westphalia created a new European order of equal sovereign states.

In international law, sovereignty means that a government possesses full control over affairs within a territorial or geographical area or limit. Determining whether a specific entity is sovereign is not an exact science, but often a matter of diplomatic dispute. There is usually an expectation that both de jure and de facto sovereignty rest in the same organisation at the place and time of concern. Foreign governments use varied criteria and political considerations when deciding whether or not to recognise the sovereignty of a state over a territory. Membership in the United Nations requires that "he admission of any such state to membership in the United Nations will be affected by a decision of the General Assembly upon the recommendation of the Security Council."

Sovereignty may be recognized even when the sovereign body possesses no territory or its territory is under partial or total occupation by another power. The Holy See was in this position between the annexation in 1870 of the Papal States by Italy and the signing of the Lateran Treaties in 1929, a 59-year period during which it was recognised as sovereign by many (mostly Roman Catholic) states despite possessing no territory – a situation resolved when the Lateran Treaties granted the Holy See sovereignty over the Vatican City. Another case, sui generis is the Sovereign Military Order of Malta, the third sovereign entity inside Italian territory (after San Marino and the Vatican City State) and the second inside the Italian capital (since in 1869 the Palazzo di Malta and the Villa Malta receive extraterritorial rights, in this way becoming the only "sovereign" territorial possessions of the modern Order), which is the last existing heir to one of several once militarily significant, crusader states of sovereign military orders. In 1607 its Grand masters were also made Reichsfürst (princes of the Holy Roman Empire) by the Holy Roman Emperor, granting them seats in the Reichstag, at the time the closest permanent equivalent to an UN-type general assembly; confirmed 1620. These sovereign rights were never deposed, only the territories were lost. Over 100 modern states maintain full diplomatic relations with the order, and the UN awarded it observer status.

The governments-in-exile of many European states (for instance, Norway, Netherlands or Czechoslovakia) during the Second World War were regarded as sovereign despite their territories being under foreign occupation; their governance resumed as soon as the occupation had ended. The government of Kuwait was in a similar situation vis-à-vis the Iraqi occupation of its country during 1990–1991. The government of Republic of China (ROC) was generally recognized as sovereign over China from 1911 to 1971 despite the 1949 victory of the Communists in the Chinese civil war and the retreat of the ROC to Taiwan. The ROC represented China at the United Nations until 1971, when the People's Republic of China obtained the UN seat. The ROC political status as a state became increasingly disputed; it became commonly known as Taiwan.

The International Committee of the Red Cross is commonly mistaken to be sovereign. It has been granted various degrees of special privileges and legal immunities in many countries, including Belgium, France, Switzerland, Australia, Russia, South Korea, South Africa and the US, and soon in Ireland. The Committee is a private organisation governed by Swiss law.