The argument is that they already served their sentence. They are free to do as they will. This is effectively in addition to their sentence, retroactively changing the laws. Imagine if suddenly there was a law that said you were to have your tongue cut out if you lied, and that it applied to lies told in the past. How would you feel about that?<p>The point is, punishments can only be applied to sentences pronounced from this point on, not ones that have already been served or are in the process of being served.