On September 24, 1596, a Royal Provision (a measure or proclamation falling somewhat short of a law but more important than a mere regulation) awarded two individuals, Domigo Olabe and Santiago Madariaga, the exclusive right to exploit the whole territory of Bizkaia for the mining of gold, silver, lead, tin, and copper. The Seigniory of Bizkaia, through its own government, opposed the measure on the grounds that it breached the Fuero or Law of Bizkaia, the legal codification that established the basis on which the Seigniory retained jurisdiction over a wide range of matters and formed part of the Castilian political orbit. In turn, the Seigniory took legal action against the decision in a case that lasted just short of 200 years! In November 1791 the case was settled in Bizkaia’s favor.
Information taken from Iñaki Egaña, Mil noticias insólitas del país de los vascos, p. 102.
For more information on the intricate system codified in the Fuero, check out Gregorio Monreal Zia, The Old Law of Bizkaia (1452): Introductory Study and Critical Edition.