 The Estrada Doctrine as the most influential and representative instrument in this field, proclaimed in the early 1930s and strictly applied until 2000, claimed that foreign governments should not judge, positively or negatively, the governments or changes in government of other nations, in that such action would imply a breach to their sovereignty.This policy was said to be based on the principles of non-intervention, peaceful resolution of disputes and self-determination of all nations.During the first presidency of the National Action Party, Vicente Fox appointed Jorge Castañeda to be his Secretary of Foreign Affairs.