The Path of the Law

In this selection of The Path of the Law, Holmes explains how the law should be viewed and how there is a difference between the legal aspects and moral ideas. Holmes says, "The reports of a given jurisdiction in the course of a generation take up pretty much the whole body of the law, and restate it from the present point of view. We could reconstruct the corpus from them if all that went before were burned." If i am understanding this correctly, does he also explain how the law should change over time with our evolving legal systems and forever changing point of view? If that is so, then we would have to let some people go free once they change. For instance if they were to legalize marijuana, then they would have to let all the people that are locked up for marijuana distribution go free, right?