What is Antithetarius?

Legal Definition
Old English law. The name given to a man who endeavors to discharge himself of the crime of which he is accused, by retorting the charge on the accuser. He differs from an approver (q, v.) in this, that the latter does not charge the accuser, but others. Jacob's Law Dict.
-- Bouviers Law Dictionary
Legal Definition
In Old English law. A man who endeavors to discharge himself of the crime of which he is accused, by retorting the charge on the accuser. He differs from an approver in this: that the latter does not charge the accuser, but others. Jacob.
-- Black's Law Dictionary
Legal Definition
One seeking to escape punishment for a crime by charging his accuser therewith.
-- Ballentine's Law Dictionary