Lex Talionis 
(law of retaliation). This was a Roman law to the effect "That if any one called another man's credit, or fortune, or life, or blood into question in judgment, and could not make out the crime alleged against him, he should suffer the same penalty that he intended to bring upon the other." Although the ecclesiastical law could not inflict the punishment of retaliation for false witness against any man's life, yet such false testimony was early reputed by the Church as the highest species both of calumny and murder, and consequently brought such witnesses under all the ecclesiastical penalties due to those crimes. Bingham, Christ. Antiq. bk. 16:ch. 10: 9.