First, it was designed to restrain man's vindictiveness, and second it was designed to be administered as the justice of a formal court. We need to go back to the days when there was no police force. When someone injured you, your first angry reaction was to go and injure him. And not just to the extent that he injured you. Hurt him so badly that he'll never forget it.
Anger is vile when it is aroused.
Modern jurisprudence is based solidly on this sort of principle. The point here is to restrain man's vindictiveness, not encourage it. Obviously it is the court that is administering the punishment, not the individual who was injured. A matter must be established by the testimony of two or three witnesses. If a malicious witness takes the stand to accuse a man of a crime, the two men involved in the dispute must stand in the presence of the Lord before the priests and the judges who are in office at the time.