Banco de Vizcaya v Don Alfonso de Borbon y Austria is a notable case in the field of international law, specifically in relation to the doctrine of state immunity.
The case was heard by the House of Lords in 1935, and it concerned a claim made by the Banco de Vizcaya, a Spanish bank, against Don Alfonso de Borbon y Austria, a member of the Spanish royal family.
The case arose out of a loan made by the Banco de Vizcaya to a Spanish company, in which Don Alfonso was a shareholder. When the company defaulted on the loan, the bank sought to recover the debt by seizing assets belonging to Don Alfonso but held by his agent in London. Don Alfonso argued that as a representative of the Spanish state, he was entitled to immunity from legal proceedings in the UK.
The House of Lords held that Don Alfonso was indeed entitled to immunity from legal proceedings in the UK, on the grounds that he was a representative of the Spanish state. The court held that the principle of state immunity, which had long been recognised in international law, applied to all states, regardless of their form of government. The court emphasised that the principle of state immunity was based on the principle of comity, which required that states should not interfere in the affairs of other states. As a result, the claim by the bank was dismissed.