Why banks won't work with legal marijuana industry -
Due to a provision in the Controlled Substances Act, banks that do business with legal marijuana sellers are at risk of losing their deposit insurance or federal charter. In an attempt to mitigate the problem, the Obama administration released a new set of guidelines in February giving banks a tentative go-ahead. Unfortunately the new rules don't actually offer banks immunity from prosecution.
https://mic.com/articles/86347/meet-potcoin-the-cryptocurrency-that-could-solve-the-marijuana-industry-s-biggest-problem#.Vh8NcoMUR