There is a power greater than Benedict/Ratzinger, a power greater than the pope on earth and that is called a Ecumenical council. When a Ecumenical council gathers they can change "the rules" of the church. The Ecumenical council in past has dethroned popes, and other times popes have been hold in line via threats to hold a Ecumenical council to dethrone the pope.

Now the victors write the history book, according to the Catholic church there has been never a pope that was "forced" out of the church. No they just "resigned" and a new pope was elected by the cardinals to replace him (for example the East/West schism, where there was 3 simultaneous popes, they weren't kicked out, no they resigned for the good of the church )

I will let someone (such as Tom) explain more about the history behind this.