in 1455, William Sinclair, Earl of Caithness gained a grant of the justiciary and sheriffdom of the area from the Sheriff of Inverness.
Prior to 1748 most sheriffdoms were held on a hereditary basis.
From that date, following the Jacobite uprising of 1745, the hereditary sheriffs were replaced by salaried sheriff-deputes, qualified advocates who were members of the Scottish Bar.
[1] In 1870 the office became known as the Sheriff of Caithness, Orkney & Shetland.
[2] It was again reorganised as the Sheriff of Caithness, Sutherland, Orkney & Zetland in 1946, but was abolished in 1975 when the current sheriffdom of Grampian, Highland and Islands was created.