The law and its practical application are always dependent on the social conditions of the respective epoch. Often, therefore, the way legal institutions were handled in the past is not obvious at first glance. This applies even more to those institutions no longer extant today, such as the Saxon purging ("Lauterung"), which can be traced back to medieval German legal practice and ends only in 1877/79 with the German Reichsjustizgesetze. Last used as legal remedy, earlier forms of purging still point to their predominant use as a mere declaration of judgment. This study is devoted to showing the reasons for the emergence, change and longevity of the institution of purging, which was practiced in the Saxon trial over the course of several centuries.