For four centuries the name Sutherland was applied only to the south-eastern portion of the modern county. In 1631 the name was extended to the whole country stretching from the Oykell and Kirkaig rivers to Caithness. For a time the Halladale river had formed the north-eastern boundary but in that year the modern boundary, extending from Drumhollistan to the Ord, was finally fixed.
The erection of Sutherland into a county was achieved by Sir Robert Gordon, who was ambitious to raise the prestige of his family above that of such neighbouring barons as the Earl of Caithness and Lord Reay.
Earlier grants of jurisdiction had been made to the Earl of Sutherland both by the Crown and by the Earl of Huntly, Sheriff of Inverness. In 1503 law courts were appointed by act of Parliament to he held at Dornoch. These courts, however, were established merely to save litigants the expense of long and dangerous journeys to Inverness, for Inverness-shire then included the whole of Ross, Sutherland, and Caithness. In 1583 the Earl of Huntly made a grant to his relative the Earl of Sutherland of that part of his jurisdiction consisting of the sheriffship of Sutherland and Strathnaver. The Earl of Sutherland thus acquired the jurisdiction of Sheriff over all persons residing upon his own lands. In 1601 a royal charter was obtained confirming to the Earl of Sutherland many old grants and privileges including the regality of Sutherland given in 1347 by David II and the grant of 1583.
In 1631, under a crown writ granted by Charles I, the sheriffdom of Sutherland was severed from Inverness and the lands of the earldom of Sutherland, together with Assynt and the other baronies lying between Ross and Caithness, were formed into a shire. Dornoch was appointed to be head burgh of the new shire and the seat of justice in all time corning, The tenacity with which the nobles clung to their feudal privileges is indicated by the fact that in the royal writ of erection special reservation is made to the Earl of Sutherland of the privilege of pit and gallows within his own proper lands as a right apart from the sheriffship. The Scots Parliament confirmed the new erection in 1633.