Formerly, when a person was accused of a crime or sued in a civil action, he might purge himself upon oath of the accusation made against him whenever the proof was not the most clear and positive; and if upon his oath he declared himself innocent, he was absolved.
This usage, so eminently calculated to encourage perjury by impunity, was soon found to be dangerous to the public safety. To remove this evil the laws were changed by requiring that the oath should be administered with the greatest solemnity; but the form was soon disregarded, for the mind became easily familiarized to those ceremonies which at first imposed on the imagination, and those who cared not to violate the truth did not hesitate to treat the form with contempt. In order to give a greater weight to the oath of the accused, the law was again altered so as to require that the accused should appear before the judge with a certain number of his neighbors, relations or friends, who should swear that they believed the accused had sworn truly. This new species of witnesses were called compurgators.
The number of compurgators varied according to the nature of the charge and other circumstances.
By the English law, when a party was sued in debt or simple contract, detinue, and perhaps some other forms of action, the defendant might wage his law by producing eleven compurgators who would swear they believed him on his oath, by which he discharged himself from the action in certain cases.