This definitely will not lead to a slippery slope or a global new world order.
Hate to break it to you, but there have been multi-lateral treaties before. Including those that deal with taxation.
Especially considering that the permanent members (which include Russia and China, as well as the US and others) are given veto powers, and they aren't afraid to use them whenever convenient for them.
P.S. I don't honestly believe in the whole "global new world order" conspiracy-tier of political discourse. My reply above was just meant to illustrate that something like UN is not what the person, who originally brought up "global new world order", had in mind.