There is so much to say about this amazing teaching. Let me divide my response into two parts: “An eye for an eye”, and “Do not resist an evildoer”, Jesus’ program for nonviolent resistance to injustice. I will post each separately and invite your comments as we go along.
The phrase “An eye for an eye” originally comes from Exodus 21:23-27, where a person who has taken the eye of another in a fight is required to forfeit his own eye as compensation. This is called reciprocal justice, lex talionis, and can be traced back to the Code of Hammurabi. By the time of Jesus lex talionis was understood in financial terms, with the guilty party paying a fine sufficient to cover damages, pain, medical expenses, incapacitation, and mental anguish.
Your reference to Deuteronomy 19:16-21 deals with a more direct form of lex talionis where conspirators testifying falsely in court are punished by having done to them what they planned to do to their intended victim. Deuteronomy also mentions the case of a woman coming to the aid of her husband in a fight by grabbing the genitals of her husband’s opponent. The Torah says “you shall cut off her hand; show no mercy” (Deuteronomy 25:11-12). This severe reaction to “hitting below the belt” most likely reflects Iron Age fears about women touching men’s genitalia, but by the time of Jesus this case was understood to refer to a woman who was going to kill her husband’s attacker rather than incapacitate him. Cutting off her hand was thought to be a lesser punishment, taking into account her passion to save her husband, when she might have been liable to capital punishment as a would-be murderer.
In each of these cases, however, we are talking about official justice carried out by the courts, and not acts of individual violence or revenge. Even the one exception to this rule found in Numbers involves the courts.
In Numbers 35:9-30 a person charged with manslaughter is obligated by the court to flee to a “city of refuge” to await trial. No one can touch him as long as he remains in the city. If he leaves the city, however, and is killed by a relative of the original victim, no penalty is accrued because the accused is now considered an escapee in violation of the court order to remain in the city of refuge. The idea behind this ruling is, in a world without prisons, to scare the accused into staying in the city of refuge until his trial. Notice that this only applies to manslaughter, killing without forethought or intent. Murder, intentional killing, is punishable by death, and no city of refuge applies. But in every case the court must establish guilt and carry out the sentence.
In other words, even in biblical times “an eye for an eye” was not about private revenge but court-based justice. Private revenge was already outlawed in Leviticus 19:18, “You shall not take vengeance, nor bear any grudge against the children of your people; but you shall love your neighbor as yourself” (Leviticus 19:18).
Given all of this it is challenging to figure out what Jesus intends with his attack on “an eye for an eye.” He cannot be referring to private revenge, because “an eye for an eye” doesn’t refer to private revenge but to court sanctioned punishment. So is he attacking the court system itself?
Maybe. Given the morally corrosive nature of Roman occupation, it is not hard to imagine that the justice system, like the High Priesthood, was in the pocket of Rome. Justice may simply be for sale, and the people to whom Jesus addresses his message are not those with the wherewithal to buy it.
I suggest that we are dealing with a call to abandon the corrupt courts, and find a new way to “do justly, love mercy, and walk humbly with your God,” (Micah 6:8).