Christopher Hitchens and Richard Dawkins have called for the prosecution of Benedict XVI, and the human rights lawyer Geoffrey Robertson, in an exercise of creativity, suggested that the abuse cases could be considered crimes against humanity and tried by the international criminal court (ICC). The Hague-based court has that far started investigations only into a few selected situations: most prominently the bloody conflict in northern Uganda, the atrocities in the Democratic Republic of Congo and the massacres in Sudan. It is an intriguing thought that the Vatican might be next on the list, and that the pope's next Easter mass will be broadcast from a prison cell. Only: It won't happen. Robertson probably knows that.

True enough, the ICC can prosecute sexual slavery as a crime against humanity – as well as rape and other sexual offences. But not every sexual offence falls automatically in that category. Something else needs to be in place: sexual offences only become crimes against humanity if they are done in the "context of a widespread or systematic attack directed against a civilian population". That in itself is difficult to prove (who is the "civilian population" in the abuse cases?). And there is more: the attack must be based on a "State or organizational policy". With all the horrors that abusive priests have inflicted on children in their care, it would still be a stretch of the reality to speak of a papal plan to carry out the abuse.

Outside the ICC, it is even more difficult to drag the pope into a courtroom. In national courts, Benedict XVI enjoys the highest form of immunity that international law gives to individuals: the immunity of a Head of State. Papal critics see that differently: they are not convinced that the Vatican really qualifies as a State.

In international law, reference is usually made to four elements which "make" a State: a defined territory, an effective government, a permanent population and the capacity to enter into international relations. The Vatican has all four, but in rather eccentric forms. Its territory is well defined, but tiny (it is the smallest State on the planet). It has a government – well structured and effective, but not exactly democratic (it is an absolute monarchy). Vatican City is permanently populated, and there is such a thing as Vatican citizenship: but it is a small population, and quaintly composed (mainly clergy and the Swiss Guard). It certainly has the capacity to enter into relations with other States. In fact, it has done so frequently, and that is a crucial point: the Holy See (representing the Vatican) has relations with more than 170 States. Wherever papal diplomats are received, they enjoy immunity from criminal law – just like diplomats from any other State. The Vienna Convention on Diplomatic Relations, to which almost all States are party, expressly refers to papal representatives (nuncios and internuncios). It would be absurd if the representatives of the pope had immunity, but not the pope himself.

In international law, a sense of the realities not an altogether bad idea. That the church has let its members down, is beyond question. That those who actually carried out the crimes, must face justice, is likewise clear. But utopian dreams about the pope in an iron cage help no one – least of all the victims of abuse.