The concept is based on the ancient Roman lustrum rituals, a cleansing or purification of an individual or community through the removal of pollution. Lustration is often associated with the transition from an authoritarian regime to democratic governance, and in particular with both the denazification of post-WWII Germany and the post-communist transition to democracy in Eastern Europe following the collapse of the Soviet Union. Lustration was originally implemented as a part of the administrative reforms imposed by the Allies in post-WWII Germany and Japan, and by states in Western Europe that were formerly occupied by the Nazi regime.