Hey I'm not a diplomat but I believe the problem with this specific problem is that in the the case of 'right to clean environment' how to you protect your rights? Do you sue your neighbor for litter or the company down the street for emissions? How do you prove that emissions are out of control? Also how do developing nations who may not have the legal strength who are just as affected by pollution from developed nations exercise their rights?

Now the question of a slippery slope could be that with a right to clean environment developed nations could stifle growth and innovation in developing nations citing clean environment worries (maybe Nigeria and oil). This could go way deeper than oil however as any country trying to harvest any sort of natural resource can face scrutiny and potential action. In an extreme example developed nations could then say 'we will mine these resources because we can do it less intensively' robbing nations of potential nation building revenue. How would you combat this? Maybe a 'right to develop' and boom rights dilution and authoritative in nature. Perhaps am extreme example but extreme isn't too far with people involved.

This being the UN, I don't think there's going to be many legal intricacies because it's mostly a debate forum with little to no strings attached. Even ICC rulings serve more of a ceremonial/PR role than an actual court ruling: The world has judged you and very publicly found you guilty of stuff, but it's really up to the Security Council countries' own governing bodies to do something about that.

As things stand, what this decision does is make it look like the UK has a vested interest in polluting the world, which makes exactly 0 sense to me from a foreign policy POV: this is not something countries want to look like they stand for.

Hence my asking, I just can't make the decision or the arguments behind it make sense?