From the CSP site…
1305 Stannary Charter. Recognised right of Stannaries to its own independent legal system. Customary Rights.
(See 1198 Laws and Customs of the Stannaries, Thomas Pearce 1725.)
1337-1338 Duchy Charters. Creation of Duchy of Cornwall – "The Stannaries" included as a pre-existing Cornish organisation. Government of Cornwall continued much as before with Stannary Court and Stannary Parliament or convocation meeting when necessary.
There would have also been a dual role of the Cornish Convocation dealing with the administration of Cornwall not simply restricted to the management of Tin Mining industry e.g. Duchy Charter refers to "Court of Stannary and Mines" Indicative of dual function.
1485/1497
There is a state emergency centring on Duchy of Cornwall as a Plantagenet institution could not survive past 1485 into the Tudor era.
Tudor Henry VII possibly unconstitutionally makes his son, Arthur, Duke of Cornwall, contrary to provisions of Duchy Plantagenet Charter.
Cornish people regarded the Tudor Arthur as a usurper or fraud and rebelled against all ordinances proclamations and taxes imposed by the Dukes.
Additionally Cornish were subject to heavy taxation by Henry VII to fund war with Scottish Celts which they resented and was contrary to the spirit of 1305 Charter.
For a period of 11 years the Cornish stopped production of tin. This caused a large loss of Revenue and forced the King to enter into discussions with Cornish.
1508
This was main reason for the agreement that became the 1508 Charter.
This reaffirmed previous rights, pardons people involved in previous activities. Fresh start for Cornwall. Reaffirmed the Customary right to a Cornish parliament.
Also included provision that any Acts of Parliament had to be approved by the Stannary Parliament.
Tin production recommences.
Extracts from the British Mining World Heritage Document in support of Cornish National Minority Culture.
WHD – The Stannary system included dedicated courts and a convocation (later a parliament). A main seat of the administration was the elaborate Duchy Palace complex established in the 1290’s in Lostwithiel. Some parts of the Medieval building survive within the planned medieval town. (WHD p.125).
WHD – In 1497 the Cornish revolted against new Stannary laws imposed by Prince Arthur, Duke of Cornwall. As a result the Charters were confiscated, to be renewed by the Charter of Pardon issued in 1508 in return for a payment of £1,000.00. This included the right, through the Stannary Parliament, to veto any statute or proclamation which was ‘to the prejudice’ of the tinners. (WHD p.125