The succession of states theory asserts that all possessions and territory held by a state are automatically transferred to the state which succeeds it.

For example, if the government of the United States were overthrown tomorrow, and replaced by a newly formed Kingdom of Ongo Bongo, all of the previously controlled territory, weapons, and wealth of the former U.S. government would fall under the control of the government of the new kingdom. In other words, the new state of Ongo Bongo would, in theory if not in fact, assume all the powers of the state it just demolished.

One recent example happened when the Union of Soviet Socialist Republics dissolved in 1991: the Russian Federation was declared the USSR's successor state and acquired the USSR's seat as a permanent member of the United Nations Security Council.

This logic has been frequently used in the past by revolutionary governments such as Cuba and the former Soviet Union.

The theory has its root in 19th century diplomacy. Some critics argue the succession theory is weak for it allows few boundaries between eras allowing archaic claims to subvert popular will.

In general the theory is followed in the world community: a new government might be distasteful to others but pragmatically it must be recognized if it de facto controls the territory. There are several fairly recent examples where succession has not been smoothly adhered to:

• When the Democratic Kampuchea regime of Pol Pot was militarily displaced by the Vietnamese-backed People's Republic of Cambodia, the United Nations seat continued to be held by Democratic Kampuchea for many years.

• The Taliban state (the Islamic Emirate of Afghanistan) in Afghanistan became the de facto government of nearly all the country; but the Northern Alliance was still recognised by many nations and retained the UN seat

• When four of the Socialist Federal Republic of Yugoslavia's republics have seceeded from it, the remainder, then renamed to Federal Republic of Yugoslavia, might have been expected to inherit perquisites such as Yugoslavia's United Nations seat or Yugoslavia's assets abroad, but was in fact not allowed to by other states.

• Even though the People's Republic of China overthrew the Republic of China in 1949, the ROC continued to hold its UN seat until 1971. Notably, the ROC, which is now often acknowledged as Taiwan and continues de-facto existence, does not have a seat yet, nor has it changed its name.

Succession of states theory has yet to become an international law. It stayed as a theory since Vienna Convention on Succession of States in respect of Treaties never entered into force.[1]