Under which legal framework? Common law? Civil law? Old Testament law? Sharia law? The framework laid out by the Constitution of the Soviet Union? The US codex of law, circa 1953? Circa 2007? Circa Citizens United?
Should everyone get a chance to vote for choosing it? Should we decide based on population of respective countries? Or do a one-country-one-vote thing? Maybe one dollar of GDP, one vote? Why should Chinese commercial law have any bearing on a trade dispute between Honduras, Belgium, and Spain?
Multi-national binding protocols have been done in the past and will be done in the future. Where the international community sees it necessary, there can be the creation of international law. Certainly this case is something for which international law and enforcement regimes can be created.
They are all the products of bi-lateral or multi-lateral treaties, hammered out in secret meetings between senior members of participating governments.
There is absolutely no "International community" involved in this process. It's a private settlement between directly affected parties.
These agreements also tend to be incredibly undemocratic, and are often hilariously hostile to the interests of the constituents of said governments. Be careful what you wish for - what you'll get is less like the European Union, and more like the TPP.
Something like this has existed since league of nations days. The model appears to be a convention which individual states accept and pass into their national laws, and then a tribunal to adjudicate on disputes about the terms of the convention - so the tribunal only sees a small number of cases. Not routine stuff.
It's really not. The Paris agreement focused on the particulars of one case. Deciding a single case is much easier then building a legal framework out of whole cloth.
Should everyone get a chance to vote for choosing it? Should we decide based on population of respective countries? Or do a one-country-one-vote thing? Maybe one dollar of GDP, one vote? Why should Chinese commercial law have any bearing on a trade dispute between Honduras, Belgium, and Spain?