Legalization requires a whole framework of laws to be created. You could piggyback off cigarettes of alcohol, but should you? Those are the discussions that will be heard over the next sever months.
I also think that many people way overestimate the importance of international law and treaties. There is no court with any teeth on these things, and nobody gets any brownie points for following treaties. The only enforcement mechanism is what other countries care to do about any violations they perceive, which could be anything from nothing at all for blatant violations to sanctions, trade war, or real war for minor violations or even not going along enthusiastically enough.
http://www.theguardian.com/world/2016/mar/24/uruguay-legal-m...
Since July 2001, all drugs are legal subject to personal consumption limits.