Decisory oath

According to John Henry Merryman, "The Decisory Oath worked in the following way: Party A could put Party B on his oath as to a fact at issue that was within Party B's knowledge. If Party B refused to swear, the fact was taken as conclusively proved against him. If Party B swore, the fact was taken as conclusively proved in his favor." Mary Gregor explains that this procedure was "designed to protect the judge from threats from the wealthy and the powerful."