That having been said, wasn't there an article yesterday about how 30% of Californian pollution comes from China? Or a few weeks ago that radiation from Japan is hitting our shores? This is not what they meant with "Think locally, act globally."
Or is it on the factories / companies themselves? Is a factory in China going to sacrifice economic growth so that a Californian can breathe cleaner air? Or is a US drilling company going to buy more expensive formulas so that Mexico city can have clean water someday? These things won't happen on their own.
Ultimately that's the problem, in my opinion.
The US agreed to make one of the biggest De-salination plants in the world just before the border and now the US pays about $300/ton to clean up the Colorado River before it flows into Mexico.
That says the plant is not currently operating. It also says that it's only "included" in the water sent to Mexico. I don't see any indication that it's used for anything close to the full volume of the Colorado River.
https://maps.google.com/maps?ll=32.727761,-114.704905&z=15&t...
Basically, imagine you have a glass of chocolate milk. You take a teaspoon of chocolate milk out and put a teaspoon of regular milk back in, you will reduce the chocolate content of the glass. The glass is the river as a whole, the plant only treats the teaspoon.
That doesn't really answer how it would enforce anything; sure, in that case, the US may have chosen to do something, but if it hadn't, its not like winning a case at the ICJ would have forced the US to do anything.
Consider, e.g., Nigaragua v. United States. [1]
But regional powers already have a lot of trouble keeping good relations with other countries and often have dirt of their own (see the UN), so these alliances are usually ineffective for anything but trade regulations.