the catholic church has the oldest continuously functioning legal system in the western world, predating the evolution of modern european civil law and common law systems. the 1983 code of canon law governs the latin church "sui juris". the eastern catholic churches, which developed different disciplines and practices, are governed by the "code of canons of the eastern churches". the canon law of the catholic church influenced the common law during the medieval period through its preservation of roman law doctrine such as the presumption of innocence.