In the past I have pointed out the problems with the concept of guilt imputation upon which penal substitution depends. (See for example, “The Death of Jesus, the rape of a woman, and a concept called ‘Imputation’” and “A footnote on guilt imputation.”) The problem is that guilty is not transferable between parties. If Jones commits a crime, the criminal penalty for the crime must be borne by Jones. It cannot be borne by another party, even if the other party is willing to shoulder the penalty. In short, the maxim is, “You do the crime, you do the time,” not “You do the crime, somebody does the time.”
This simple and intuitive principle was illustrated yet again when news broke today of the case of Juan Silva Sr. who was arrested for a fatal hit-and-run in 2013 after he turned himself in to police. It turns out that Silva issued a false plea two years ago in order to protect his 22 year old son who was, in fact, the perpetrator of the crime. (You can read more about the case here.)
Some people may admire Silva for his commitment to his son while others will focus solely upon his subversive attempt to deceive the court. But all are agreed that justice is not served when a father willingly goes to prison for his son’s crime. An act like this does not serve the cause of justice.
This leaves the defender of penal substitution and its imputation theory of guilt either searching for an analogy to illustrate the logic of this application of justice or rejecting the fundamental intuition that guilt is not transferable. Neither option appears very promising.