The idea of a member of the royal family appearing in court is unusual, anywhere. We can only recall one such attempt in Thailand, back in 1933, as described in Kasian Tejapira’s Commodifying Marxism: The Formation of Modern Thai Radical Culture, 1927-1958:
That case is also briefly mentioned in this set of documents (clicking opens a largish PDF) as a case involving the alleged libel of Pridi Phanomyong by the then king.
So it is that a report at The Guardian is of interest for it covers a corruption case and the involvement of King Juan Carlos’ daughter, Princess Cristina, who is now “formally named as a suspect in a court investigation.” This case is interesting for Spain maintains a lese majeste law and has notions of inviolability as well.
The report states that this “dramatic decision by investigating magistrate José Castro will see the princess called to give evidence at a courthouse in Palma de Mallorca, capital of the Balearic Isles, on 27 April.” It adds that the “decision is a blow for King Juan Carlos, as a once model royal family begins to buckle under the weight of public scandal.” The case revolves around alleged special deals by her husband and the access and apparent impunity his royal connection provided.
Left and republican parliamentarians have “welcomed the decision to make the princess – who will visit the court on a Saturday so that special security measures can be set up – declare before the investigating magistrate.”
Political Prisoners in Thailand 