Before he was elected Pope, Cardinal Ratzinger headed the Congregation for the Doctrine of the Faith for 24 years. The Vatican’s own documents state: “The duty proper to the Congregation for the Doctrine of the Faith is to promote and safeguard the doctrine on the faith and morals throughout the Catholic world: for this reason everything which in any way touches such matter falls within its competence.”
Any abuse scandal that came up between 1981 and 2005 would have crossed Ratzinger’s desk. Unless Vatican has invested in high quality shredders, the Pope may be down to about 85% infallibility.