meaning what? toothless is still toothless even using words like must. what happens if majority individuals do not? last I checked, the US still hasn't signed the same agreements about ICC or ICJ.
The united states signed on to the ICJ in 1945.
Some treaties have optional parts where you can defer disputes to the icj. The united states is a party to some of those but not all of them. But that is really a separate thing from the ICJ.
The ICC is very different from ICJ. USA has been pretty hostile to the icc since the get-go.
"...in which countries must sign on [if they want the treaty to have legal standing within their jurisdiction]"