This law applies in a limited number of cases. Let’s look at them:
1. Ex. 21:22-27 the unintentional injury of a fetus when men are striving together
2. Lev. 24:19-20 the injury of a neighbor
3. Deut. 19:16-21 acting as a false or wicked witness in a case before judges
The first establishes God’s legal view of the fetus as one whose injury must be recompensed even when the harm was unintentional! The life of the fetus is not worth 1/3 the value of the life of the one who injured the fetus: they are equals. Short lives are not less valuable. Small eyes, hands, or teeth cost exactly the same as their adult counterparts. Life is life with legal protection in or out of the womb.
In the second case, as in the first, the law establishes legal limits of liability. If I injury my neighbor’s hand, he cannot take my life for the sake of his hand, but he can take my hand or the value thereof as our courts handle it.
The third case is my favorite: if a false or wicked witness testifies against someone for a capital crime and it becomes known, the false or wicked witness gets the capital punishment. Jesus accuses the accusers of the woman caught in adultery of being wicked witnesses, witnesses who actually were involved in committing the crime. Knowing that wicked witnesses earn the same sentence they seek for another, every single wicked witness left. Not a single person there was a witness who was not involved in the crime. Not a single person was willing to testify against her, “condemn” her. Obviously, Jesus could not condemn her since he was not with the people who brought her to him. He was not an eye witness, and even if he had witnessed it, capital crimes need to be established by the testimony of two or three witnesses. What amazing grace in the Torah of God!