There is work towards that end in Mexico. A selected few got a Supreme Court ruling that supports the legal use and growth of marijuana for personal use [1]. It didn't make it legal, but it sets precedence and a framework to keep the wheel moving to eventually make it legal like in other countries. Through this very same process last year the whole country make it same-sex marriage legal.

[1] https://www.nytimes.com/2015/11/05/world/americas/mexico-sup...