Already two Italian courts have ruled against Vatican prosecutors in their wide-ranging corruption investigation, which has highlighted the incompatibility of the Vatican justice system with European norms. 

In the case before the Milan appeals court, lawyers for Cecilia Marogna, a self-described intelligence analyst, are expected to argue that she shouldn't be extradited to the Vatican because there's no extradition treaty between the two states. Another possible argument is that without such a treaty, Italian law bars sending citizens to a country where their “fundamental right” to a fair trial isn't guaranteed. 

Defence lawyers who have worked in the Vatican's criminal justice system say its procedures are outdated, don't provide adequate rights for the accused and are subject to arbitrary interference by the pope, who as absolute monarch exercises exclusive legislative, executive and judicial power. 

In the broader corruption investigation, for example, Pope Francis authorized a procedure that precludes oversight of prosecutors by an independent judge during the investigative phase. There is also no chance for the defense to contest testimony obtained during the investigation or evidence seized during searches, as would be required in Italy. 

Vatican prosecutors insist the rights of the accused are safeguarded, and that the pope had to order the “summary rite” in this case because of a technicality owing to the old legal code in use. 

In the spinoff case involving extradition, Vatican prosecutors have accused Marogna of embezzlement and misappropriation of Holy See funds. They say Marogna was paid at least 575,000 euros by the Vatican secretariat of state from 2018-2019 to help liberate Catholic hostages, but that the money was used instead to buy Prada, Chanel and other high-end luxury goods.