In the late Middle Ages, the distinction between human law and natural law was frequently blurred, leading to the surreal historical phenomenon of animal trials. One of the most famous instances occurred in Basel, Switzerland, in 1474, when a farmyard bird was formally arrested, jailed, and brought before a magistrate. The crime?
Laying an egg. To modern sensibilities, an egg-laying bird seems entirely ordinary, but medieval demonology held a terrifying belief regarding such events. It was feared that an egg laid by a male bird, or produced through unnatural witchcraft, was a basilisk egg.
According to folklore, if such an egg were incubated by a toad or serpent, it would hatch a basilisk or cockatrice—a mythical beast capable of killing humans with a single glance or breath. The citizens of Basel were taking no chances. A defense advocate was appointed for the creature, who argued that laying an egg was an involuntary biological act rather than a conscious crime, meaning no evil intent could be proven.
However, the city prosecutor successfully argued that the act itself posed an existential demonic threat to the public safety of Basel regardless of intent. The bird was found guilty of committing an unnatural act inspired by Satan. In front of a crowd of curious onlookers, the condemned bird and its suspicious egg were formally executed by being burned at the stake at the top of the Kohlenberg hill.
This trial remains one of the best-documented examples of medieval zoomorphic prosecution and public anxiety surrounding dark arts.