According to the International Tribunal into Crimes of Church and State, the reason for the resignation of Pope Benedict XVI, is an arrest warrant against him for crimes against humanity and criminal conspiracy.
On ITCCSs official website, they mention that on February 1 of this year a few representatives in the European nation issued an arrest warrant against Joseph Ratzinger (Pope Benedict XVI). The document would then be presented on February 15 at the Vatican which would allow this nation to detain the Pope and question him about these charges.
A diplomatic note was issued to the Vaticans Secretary of State, Cardinal Bertone Tarciso, on Monday, February 4, which invited the Vatican to comply with the order, but there was no response. Six days later, Joseph Ratzinger resigned as leader Catholic Church.
The announcement of the arrest warrant that was issued coincides with confirmation that was also made by the Vatican this weekend, which dictates that Ratzinger will have legal immunity as long as he stays within the bounds of the Vatican nation, for that reason, a request for extradition was also made.
Furthermore, whoever is elected as the new Pope could also be affected by this warrant as well. The ITCCS also indicated that there is a request for a commercial lien against the entire Roman Catholic Church.