For centuries and across multiple continents, an accused person might be told to plunge an arm into boiling water or carry red-hot iron to prove innocence. This episode traces trial by ordeal from the Code of Ur-Nammu and the Code of Hammurabi through medieval Europe, explaining the concept of judicium Dei, the judgment of God, and why societies without forensics or paper trails outsourced verdicts to what amounted to a divine polygraph.

We then look at economist Peter Leeson’s argument that the ordeal was a rational sorting mechanism: the guilty, certain God would not save them, confessed or settled, while the innocent volunteered, and priests who controlled the fire and water quietly let things cool. That explains the surprisingly high exoneration rates in medieval records, and why Pope Innocent III’s 1215 ban on priestly participation collapsed the whole system.

• King Athelstan’s one-fold and three-fold ordeals, with the stone at wrist depth or elbow depth depending on the crime
• Peter Bartholomew’s fatal walk through fire during the First Crusade and Michael Palaiologos’s clever escape from the hot iron
• How the cold water test flipped during the witch hunts, so that floating meant guilt
• Poison ordeals such as Madagascar’s tangena nut and the Calabar bean, plus bread-and-cheese and Eucharist trials
• Historian Peter Brown’s view of ordeals as controlled miracles that prevented blood feuds