The Supreme Court has agreed to examine a claim by a Belgian woman, Ingrid Sartiau, that she is the illegitimate daughter of ex-King Juan Carlos, who abdicated last summer.
Ingrid Sartiau claims her mother had an affair with Juan Carlos in the 1960s, while he was married and a crown prince. The case can only now be heard because the king lost his immunity from prosecution after his abdication.
The court rejected a separate claim by Alberto Sola, born in Barcelona in 1956, who said his mother also had an affair with Juan Carlos.
Juan Carlosnow has 20 days to respond to the suit. The former king could be asked to take a paternity test and the case could go as far as a public hearing.
The two paternity cases had been rejected by the courts in 2012 while Juan Carlos still had immunity from prosecution, but this all changed following his abdication. He still has generous, but not total, immunity from the laws of the land and can still be prosecuted by the Supreme Court.
Although parliament agreed to give the former him a level of immunity after abdication, it gave the supreme court the authority to prosecute him.
The former king is no stranger to controversy, there having been numerous reports of infidelities as well as ill-advised hunting trips and other scandals.