The Cornish Foreshore Case was an arbitration case held between 1854 and 1858 to resolve a formal dispute between the British Crown and the Duchy of Cornwall over the rights to minerals and mines under the foreshore of Cornwall in the southwest of England, most of which was owned by the duchy.

[1] The Duchy of Cornwall presented a series of assertions regarding its sovereignty and territorial rights.

Thomas Pemberton Leigh, Baron Kingsdown (during the course of the debate elevated to the peerage) represented the duchy.

The problem which gave rise to the dispute was explained by the Solicitor-General during parliamentary debates on the Cornwall Submarine Mines Bill, on 19 July 1858: "the whole of the soil, and every thing under the soil, between high and low water mark on the shores of the kingdom, belonged to the Crown; and in numerous instances that right had been granted away, or passed to individuals by adverse possession against the Crown.

That doubt had been further increased by innumerable dealings which had since taken place between the Crown and the Prince of Wales in the shape of statutes, other charters, and deeds of various kinds.