In 19:15-21 there is a word about the judgment of any iniquity or any sin.
The judgment of any iniquity or any sin was to be done at the word of two or three witnesses (v. 15). It was not adequate to have just one witness. Two were required, and it was better to have three.
If a malicious witness rose up against a man to testify against him of wrongdoing, the two men who had the dispute were to stand before Jehovah, before the priests and the judges (vv. 16-17).
The judges were to investigate the matter thoroughly (v. 18a).
If the witness was a false witness, one who testified falsely against his brother, the children of Israel were to do to him as he intended to do to his brother (vv. 18b-19a).
By the people's doing to the false witness what he intended to do to his brother, the evil would be utterly removed from the midst of the children of Israel (v. 19b).
Those who remained would hear and would fear and would never again do anything like that evil in their midst (v. 20). This kind of criminal judgment thus became a warning to the rest of the people.
Their eye was not to pity. Instead, there was to be "life for life, eye for eye, tooth for tooth, hand for hand, foot for foot" (v. 21).