The stannary parliaments and stannary courts were legislative and legal institutions in Cornwall and in Devon (in the Dartmoor area), England. The stannary courts administered equity for the region's tin-miners and tin mining interests, and they were also courts of record for the towns dependent on the mines. Executive authority in stannary areas was exercised by the Lord Warden of the Stannaries.
The separate and powerful government institutions available to the tin miners reflected the enormous importance of the tin industry to the English economy during the Middle Ages. Special laws for tin miners pre-date written legal codes in Britain, and ancient traditions exempted everyone connected with tin mining in Cornwall and Devon from any jurisdiction other than the stannary courts in all but the most exceptional circumstances.
King John granted a charter to the tin miners of Cornwall and Devon in 1201, confirming their "just and ancient customs and liberties". The tin miners of both areas originally met together at Hingston Down and referred to themselves as a parliament. Edward I of England split the stannary institutions between Cornwall and Devon, establishing parliaments and courts for the two counties separately. The jurisdiction of the Cornwall stannary institutions covered the whole of the county, while the stannary courts of Devon had a reputation for harsh justice, and once jailed a Westminster MP (Richard Strode).
Edward I's 1305 Stannary Charter established , Ashburton and Chagford as Devon's stannary towns, with a monopoly on all tin mining in Devon, a right to representation in the Stannary Parliament and a right to the jurisdiction of the stannary courts. Plympton became the fourth Devon stannary town in 1307.