In January 897, in the Lateran Basilica in Rome, a trial began. The defendant was a former pope named Formosus.

He had been dead for about nine months.

On the orders of the new pope, Stephen VI, Formosus's body was dug up, dressed in full papal vestments and propped up on a throne to face his accusers. Because a corpse can't speak in its own defence, a young deacon was appointed to stand beside it and answer for him.

This is the event history remembers as the Cadaver Synod.

Why would anyone do this?

Rome in the late ninth century was a political battlefield. Powerful families and rival factions fought over the papacy, which brought enormous wealth, land and influence. Popes came and went with alarming speed, and many of them died violently.

Formosus had made enemies. Among other things, he had crowned a rival claimant as emperor, angering a powerful faction that Stephen VI supported. Putting Formosus on trial was a way to declare his entire reign illegitimate — and with it every appointment and decision he had made.

The sentence

The court found Formosus guilty, including of having become pope illegally. His papacy was declared null. The three fingers of his right hand that he had used to give blessings were cut off. His body was stripped of its vestments, buried in a common grave, then dug up again and thrown into the River Tiber.

The backlash

The spectacle horrified Rome. Within months, a revolt broke out. Stephen VI was deposed, thrown into prison, and strangled there in the summer of 897.

Later popes reversed the verdict and declared the trial void, and church authorities eventually banned putting dead people on trial at all.