Did William the Conqueror establish a 12 man jury?

William the Conqueror did not establish a 12-man jury in the way we understand it today. The concept of a jury evolved over time in England, with early forms of local assemblies and trial by peers existing before William's reign. However, the formalization of the 12-man jury system became more established in the later medieval period, particularly under King Henry II in the 12th century. William's legal reforms did lay the groundwork for future developments in the English legal system.