Corriere della Sera quoted from an 18-page document titled The Church and the sex abuse scandal, which was published by the German monthly Klerusblatt.
Benedict wrote that during the 1980s and 1990s, "the right to a defence was so broad as to make a conviction nearly impossible".
He took a hard line against clerical sex abuse as the Vatican's conservative doctrine chief, and later as pope, defrocking hundreds of priests accused of raping and molesting children.
Last month, Pope Francis unveiled extensive new sex abuse legislation for Vatican personnel and Holy See diplomats.
It required allegations of abuse to be reported to Vatican prosecutor immediately.
The changes came three months after the Catholic Church said it shall "never again" cover up sexual abuse perpetrated by its clergy.
Pope Francis made the promise during a Christmas address to Vatican officials in December 2018.
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