Is Penal Substitution Unsatisfactory?

It might be objected to penal substitutionary theories that punishing Christ could not possibly meet the demands of divine retributive justice. For punishing another person for my crimes would not serve to remove my guilt. The Anglo-American system of justice, in fact, does countenance and even endorse cases in which a substitute satisfies the demands of retributive justice. Moreover, Christ’s being divinely and voluntarily appointed to act not merely as our substitute but as our representative enables him to serve as our proxy before God, so that when he is punished, we are punished, to the satisfaction of divine justice.