Mighell v Sultan of Johore [1894] 1 QB 149

Action brought for a breach of promise of marriage. By Sultan of the State and Territory of Johore, otherwise known as Albert Baker

The courts of this country have no jurisdiction over an independent foreign sovereign unless he submits to jurisdiction. The fact that a foreign sovereign has been residing in this country and has entered into a contract here, under an assumed name, as if a private individual does not amount to a submission to the jurisdiction or render him liable to be sued for breach of such contract. A certificate from the foreign office is conclusive as to the status of such sovereign