[Mojave]

Starting in the 1100's.

"As we have seen the basis of Common Law was custom. The itinerant justices set out by William the Conqueror examined the different local practises of dealing with disputes and crime, filtered our the less practical and reasonable ones, and ended up with a set of laws which were to be applied uniformly throughout the country."

http://www.revision-notes.co.uk/revision/902.html

Custom, not "made up by juges".

Read a book.

[jf55510]

Then who made it up and got it to be a part of the legal system?

[Torie]

Well it was "fashioned" by judges, trying to interpret whatever was out there. If the legislature does not like such fashioning, or interpretion or existing statutory or Constitutional law, they can pass a statute, or in the US, and other nations with a Constitution and the common law tradition, amend the Consitution, if it is a Constitutional issue.

[jf55510]

From Wiki:

Before the institutional stability imposed on England by William the Conqueror in 1066, English residents, like those of many other societies, particularly the Germanic cultures of continental Europe, were governed by unwritten local customs that varied from community to community and were enforced in often arbitrary fashion. For example, courts generally consisted of informal public assemblies that weighed conflicting claims in a case and, if unable to reach a decision, might require an accused to test guilt or innocence by carrying a red-hot iron or snatching a stone from a cauldron of boiling water or some other "test" of veracity (trial by ordeal).

In 1154, Henry II became the first Plantagenet king. Among many achievements, Henry institutionalised common law by creating a unified system of law "common" to the country through incorporating and elevating local custom to the national, ending local control and peculiarities, eliminating arbitrary remedies, and reinstating a jury system of citizens sworn on oath to investigate reliable criminal accusations and civil claims. The jury reached its verdict through evaluating common local knowledge, not necessarily through the presentation of evidence, a distinguishing factor from today's civil and criminal court systems.