The United Nations follows the principle of equal voting power among member states in its decision-making organs. Weighted voting, which gives different weights to votes based on certain criteria, has been used in European federal systems since the 19th century. The Security Council requires an affirmative vote from nine out of fifteen members, including all permanent members, for substantive decisions. This system has faced criticism due to the admission of many small and sparsely populated states after decolonization.