This chapter traces the historical development of the iura novit curia principle and its contemporary application in domestic civil procedures. The analysis begins with Roman law, proceeds through the Middle Ages, and culminates in the era of the modern State. It then examines the procedural frameworks characteristic of both Continental and Anglo-American legal traditions, highlighting their respective influences on international arbitration. Finally, the chapter explores the divergent treatment of foreign law across various jurisdictions, which in turn shapes the extent to which the iura novit curia applies.