The Decretum Gratiani, also known as the Concordia Discordantium Canonum, is a foundational text of canon law compiled by Gratian around 1140. It aimed to reconcile conflicting church laws and provide a systematic framework for understanding ecclesiastical regulations, which were essential for maintaining order and justice in medieval society. The Decretum not only influenced the development of church law but also impacted the legal systems of various European regions, underscoring the intertwining of law and religion during the medieval period.