In medieval and early modern Europe, animal trials were a surprisingly formal and documented legal practice. One of the most famous cases occurred in Basel, Switzerland, where a rooster was arrested for an offense against nature: laying an egg. To the medieval mind, an egg laid by a rooster was no ordinary biological anomaly.
According to popular lore, such eggs—known as cockatrice or basilisk eggs—were believed to be incubated by toads or serpents to hatch deadly mythical beasts capable of killing with a single glance. The bird was assigned a legal defense attorney who argued that laying an egg was an involuntary physical act and lacked evil intent. However, the prosecution countered that Satan had used the animal to commit a crime against nature.
The court found the rooster guilty of sorcery and sentenced it to death. The bird, along with the offending egg, was publicly burned at the stake by the executioner in a formal public ceremony designed to reassure citizens that spiritual and civil order had been restored.