In the later medieval period the Anglo-Saxon community-based
system of law enforcement was gradually undermined by the
creation a new local official: the Justice of the Peace, or
JPs were different in two ways:
1. They were appointed by the king, not the local community.
They were thus part of central government (royal) power, which
increased through the later Middle Ages.
2. They were appointed because of their local power, wealth
and rank. They were not great magnates, and they were local,
but they were definitely not just ordinary villagers, like
the members of the tithings.
JPs gained their powers only gradually. As you can see, in
1344 they were called "Guardians of the Peace".
By 1361 they were called Justices of the Peace and allowed
the considerable expenses of 4/- (20p) a day. By the end of
the Middle Ages JPs were the mainstay of local government
and law enforcement.