“Today children of any age can be called to give evidence as their competence depends upon their understanding not their age.”
But that has not always been the case; before the 17th century children younger than 14 were deemed unreliable witnesses. Then, along came witch hunts and one particular English witch trial in which a nine-year-old girl named Jennet Device testified against her mother. Her word ensured that her entire family along with most of her neighbors were hung.
Jennet’s role in the trial was documented in a reference book for magistrates and the practice of allowing children’s testimony was adopted in the witch trials occurring in the Americas. Apparently the change was embraced: in the 1692 Salem witch trials the majority of court witnesses were children.
(via Book Slut)