To get around AG Sessions urge to enforce the laws as written, the painfully obvious solution is to change the law. This is easier that you think:
A Bill For A Law
In Congress (insert date here)By (Insert congress critter here. Include several of his friends if possible)
(1) That Title 21, §1308.11, section d, line 23 is deleted in its entirety.
(2) This bill shall take effect upon enactment.
This still requires a bit of clerical touch-up, but that's the whole thing right there. 2 lines, problem solved. Write your congress critters and ask them if they know anyone with experience in carrying legislation who would like to be the bills primary sponsor. Several states, having already legalized pot for both medical and recreational use, this shouldn't be very hard. Encourage them to then co-sponsor.