Adam Clarke on Exodus 21:24

Eye for eye - This is the earliest account we have of the lex talionis, or law of like for like, which afterwards prevailed among the Greeks and Romans. Among the latter, it constituted a part of the twelve tables, so famous in antiquity; but the punishment was afterwards changed to a pecuniary fine, to be levied at the discretion of the praetor. It prevails less or more in most civilized countries, and is fully acted upon in the canon law, in reference to all calumniators: Calumniator, si in accusatione defecerit, talionem recipiat. "If the calumniator fall in the proof of his accusation, let him suffer the same punishment which he wished to have inflicted upon the man whom he falsely accused." Nothing, however, of this kind was left to private revenge; the magistrate awarded the punishment when the fact was proved, otherwise the lex talionis would have utterly destroyed the peace of society, and have sown the seeds of hatred, revenge, and all uncharitableness.