County Durham is in North East England. The territory that became known as County Durham was originally a liberty under the control of the Bishops of Durham. The liberty was known variously as the "Liberty of Durham", "Liberty of St Cuthbert's Land" "The lands of St. Cuthbert between Tyne and Tees" or "The Liberty of Haliwerfolc". The bishops' special jurisdiction was based on claims that King Ecgfrith of Northumbria had granted a substantial territory to St Cuthbert on his election to the see of Lindisfarne in 684.
After the Norman invasion, the administrative machinery of government was only slowly extended to northern England. In the twelfth century a shire or county of Northumberland was formed, and Durham was considered to be within its bounds. However the authority of the sheriff of Northumberland and his officials was disputed by the bishops. The crown still regarded Durham as falling within Northumberland until the late thirteenth century. Matters came to a head in 1293 when the bishop and his steward failed to attend proceeedings of quo warranto held by the justices of Northumberland. The bishops' case was heard in parliament, where he stated that Durham lay outside the bounds of any English shire and that "from time immemorial it had been widely known that the sheriff of Northumberland was not sheriff of Durham nor entered within that liberty as sheriff. . . nor made there proclamations or attachments". The arguments appear to have been accepted, as by the fourteenth century Durham was accepted as a liberty which received royal mandates direct. In effect it was private shire, with the bishop appointing his own sheriff. The area eventually became known as the "County Palatine of Durham".
The prior of Durham ranked first among the bishop's barons. He had his own court, and almost exclusive jurisdiction over his men. There were ten palatinate barons in the 12th century, the most important being the Hiltons of Hilton Castle, the Bulmers of Brancepeth, the Conyers of Sockburne, the Hansards of Evenwood, and the Lumleys of Lumley Castle. The Nevilles owned large estates in the county. Raby Castle, their principal seat, was built by John de Neville in 1377.
Edward I's quo warranto proceedings of 1293 showed twelve lords enjoying more or less extensive franchises under the bishop. The repeated efforts of the Crown to check the powers of the palatinate bishops culminated in 1536 in the Act of Resumption, which deprived the bishop of the power to pardon offences against the law or to appoint judicial officers. Moreover, indictments and legal processes were in future to run in the name of the king, and offences to be described as against the peace of the king, rather than that of the bishop. In 1596 restrictions were imposed on the powers of the chancery, and in 1646 the palatinate was formally abolished. It was revived, however, after the Restoration, and continued with much the same power until July 5, 1836, when the Durham (County Palatine) Act 1836 provided that the palatine jurisdiction should in future be vested in the crown.
On the outbreak of the Civil War, Durham inclined to support the cause of the Parliament, and in 1640 the high sheriff of the palatinate guaranteed to supply the Scottish army with provisions during their stay in the county. In 1642 the Earl of Newcastle formed the western counties into an association for the kings service, but in 1644 the palatinate was again overrun by the Scottish army, and after the Battle of Marston Moor fell entirely into the hands of the parliament.
In 1614 a bill was introduced in parliament for securing representation to the county and city of Durham and the borough of Barnard Castle. The movement was strongly opposed by the bishop, as an infringement of his palatinate rights, and the county was first summoned to return members to parliament in 1654. After the Restoration the county and city returned two members each. By the Reform Act of 1832 the county returned two members for two divisions, and the boroughs of Gateshead, South Shields and Sunderland acquired representation. The boroughs of Darlington, Stockton and Hartlepool returned one member each from 1868 until the Redistribution Act of 1885.