Manor courts held by landlords for their tenants and other local people existed in their thousands across medieval England. These courts played a significant role in the everyday lives of villagers, formed a major site for the preservation of law and order, and have been studied by generations of historians. Yet room for debate remains concerning the character of these institutions in the later thirteenth and early fourteenth centuries, and the influences that proved most important for their evolution. This article uses a new database concerning hundreds of manorial personal actions – lawsuits which treated areas roughly equivalent to modern tort and contract law – to explore the procedures and practices of the manor courts, and to reconstruct their development over the first century for which detailed records of their proceedings survive. It is argued that although significant local variation among manor courts persisted, especially in the west of England, overall there was a broad process of ‘convergence’. Yet this was not simply a top-down process involving the transmission of practices from the king’s courts of common law, or the communication of external rules by legal professionals or landlords. Instead, the suitors, litigants and jurors of the manor courts played a decisive role in this process. The manorial personal actions thus provide an important instance of the fundamental role of experienced laypeople in simultaneously shaping and exploiting key institutions of medieval governance and law.