An oath is an affirmation or denial of anything _before one that hath authority to administer the same_, calling God to witness that his testimony is true (3 Inst. 165, C. 74). Sacramentum, habet in se tres comites, veritatem, justiciam et judicium; veritas habenda est in juratore; justicia et judicium in judice (Bracton, I. 4, f. 186). Four sorts of oaths have been enumerated, viz., Juramentum promissionis, where an oath is taken to do or not to do such a thing (it appears that York had taken an oath of this description); Juramentum purgationis, which is where a person is charged with any matter by bill in Equity; Juramentum probationis, where one is produced as a witness to prove or disprove a thing; and Juramentum triationis, where one is sworn to try the issue, such as a juror. The oath must be lawful, allowed by the common law or some Act of Parliament; so Salisbury says— _Sal._ It is a great sin to swear unto a sin; But greater sin to keep a sinful oath. Who can be bound by any solemn vow To do a murd’rous deed, to rob a man, To force a spotless virgin’s chastity, To reave the orphan of his patrimony, To wring the widow from her custom’d right; And have no other reason for this wrong, But that he was bound by a solemn oath? 2 _Henry VI._, Act v. Scene 1. and it must be taken before one that hath authority, not before a person acting in a private capacity, or pretending to have authority where he hath none; nor by one that goes beyond the authority which was granted. For such false oaths cannot amount to perjury in law, because they are of no validity, being coram non judice (3 Institute, 165; 4 Institute, 278, 279; 2 Roll. Alr. 257; Wood’s Institute, 2nd ed., pp. 411, 412). _Car._ The commons hast thou rack’d; the clergy’s bags Are lank and lean with thy extortions. _Som._ Thy sumptuous buildings, and thy wife’s attire, Have cost a mass of public treasury. _Buck._ Thy cruelty in execution Upon offenders, hath exceeded law, And left thee to the mercy of the law. 2 _Henry VI._, Act i. Scene 3.