I understand Colorado and Washington State have killed the laws against recreational marijuana. This raises an interesting question: will these two states release from jail the people who are there for using recreational weed?
How about expunging the records of those whose only crime was possession for use? The legal history of how we treated violators of prohibition when it was dropped might be a guide.
Releasing people from jail/prison could be a major cost savings for those two states, and an incentive for other states to follow suit.