Justiciar is the English form of the medieval Latin term justiciarius or justitiarius (meaning "judge" or "justice").
In his absence, William the Conqueror (r. 1066–1087) temporarily delegated viceroyal authority to trusted officers described variously as regent, custodian, and prefect.
"[7] The chief justiciar was responsible for directing the royal household, the curia regis, and the government departments.
He was the presiding officer of the exchequer and directed the procedures of the curia regis as the chief royal justice.
[8] The chief justiciar was invariably a great noble or churchman, and the office became very powerful and important; enough to be a threat to the king.
By the fifteenth century the chief governor was usually styled the King's Lieutenant, with the justiciar a subordinate role that evolved into the Lords Justices of Ireland.
[9] In the 12th century, a magister justitiarius appeared in the Norman kingdom of Sicily, presiding over the Royal Court (Magna Curia), empowered, with his assistants, to decide, inter alia, all cases reserved to the Crown.
[9] There is no clear evidence that this title and office were borrowed from England; it was probably based on a Norman practice instituted in both realms.
In medieval Sweden, the lagman ("lawspeaker") was the judge, or person learned in law, for a province, an area with several local district courts.
Lagmän (plural) were generally also members of the Senate of the realm, an institution corresponding to the English Privy Council.