Charles Ellicott Commentary Deuteronomy 19:15-21

"One witness shall not rise up against a man for any iniquity, or for any sin, in any sin that he sinneth: at the mouth of two witnesses, or at the mouth of three witnesses, shall a matter be established. If an unrighteous witness rise up against any man to testify against him of wrong-doing, then both the men, between whom the controversy is, shall stand before Jehovah, before the priests and the judges that shall be in those days; and the judges shall make diligent inquisition: and, behold, if the witness be a false witness, and have testified falsely against his brother; then shall ye do unto him, as he had thought to do unto his brother: so shalt thou put away the evil from the midst of thee. And those that remain shall hear, and fear, and shall henceforth commit no more any such evil in the midst of thee. And thine eyes shall not pity; life [shall go] for life, eye for eye, tooth for tooth, hand for hand, foot for foot." — Deuteronomy 19:15-21 (ASV)

Deuteronomy 19:15–21. FALSE TESTIMONY.

The law of retaliation is sternly laid down here; but it must be administered by the judges, not by men acting on their own behalf.

(17) Both the men ... shall stand before the Lord, before the priests and the judges. — This appears to mean that all cases of suspected false testimony were to go before the supreme court ; that the matter was not to be lightly decided.

Eye for eye, tooth for tooth. — This is to be effected by the award of the judges, not as a matter of private revenge. But manifestly it rests with the injured party to press the case.