A doctrine that was established by the Congress of Troppau which was held in 1820. This Congress was dominated by Russia, the Habsburg Empire and Prussia. Great Britian and France only sent ambassadors to it. In it these powers responded to the 1820-1 revolution in Spain.

The Congress stated that:

"If in states belonging to the European Alliance changes of government are produced by Revolution, and if the consequences threaten the other states, then they are excluded from the Alliance until their situation offers guarrentees of legitimate order and permanence."
Allied governments would:
"Refuse recognition of changes brought about by illegal methods (taking measures to rectify the changes) first by friendly representations, then by measures of coercion, if the employment of such coercion is indispensible."
This was an important Congress which established interventionalism as a fundamental basis for international politics. It meant it was agreed that revolution was a dangerous and undesirable thing. Hence the revolutions that occurred in Sicily and Naples in the early 1820s were repressed with the approval of the major powers. Its other significance lay in emphasising Britain's isolationist stance which was ironic considering its pivotal role in setting up the Congress system.