Trial by drowning

Trial by drowning was a historical method of punishing women susupected of witchcraft. The idea was that witches do not drown. As part of the trial the person was thrown into a lake or river or submerged under water. If the person sank to the bottom, she was innocent and hence not a witch. If she survived, she was a witch and could be hanged or executed by burning. Either way, the accused faced death.

Also see : Witchhunt, Catch-22