Among the developments in medieval England that influenced modern democratic laws was the passing of the Common law. Common law is probably the most influential series of laws to come out of medieval England.
Before it was established, many areas had different laws they were following, and with its establishment, around 1154 by King Henry II, the laws were all grouped together and a concise set of laws common to all was created. Trial by jury and even grand juries came out of this period.