California passes a statute that says that if you produce medical waste in California, you have to burn it, not just dump it somewhere. So Daniels Sharpsmart gets a ton -- actually, 320,000 pounds -- of California-created medical waste, and instead of burning it, ships it to Kentucky and Indiana, which (perhaps not surprisingly) allow medical waste to be dealt with in a much more lenient matter.
California tries to stop this scheme, but Daniels Sharpsmart sues, saying that California's attempt to regulate medical waste generated in California violates the Constitution; in particular, the dormant Commerce Clause.
The Ninth Circuit agrees.
Judge Fernandez's position is that even though California's regulating only medical waste generated in California, once you ship the stuff across state lines, there's nothing that California can do about it. He says that, otherwise, there'd be "economic Balkanization" of the Union.
A different way of looking at it would be to say that the dormant Commerce Clause sets in stone in the Constitution a nationwide race to the bottom, where the most lenient state -- the one with the fewest environmental or other protections -- sets the standard for the rest of the nation. Because why go to all the trouble to actually burn medical waste, for example, when you can just go to Kentucky, run some steam over it, and then bury the needles and other stuff. Much more convenient.
You see some of the same thing at work in transnational trade. A flow of products -- toxic waste, jobs, whatever -- to whatever nation has the least regulatory burden. Purportedly to the benefit of everyone; we dump our toxic waste in Mexico (or China, or wherever), which means it's not "our" problem anymore, and the other country gets jobs or whatever. Plus the associated tumors.
It's definitely the way of the world. So the domestic application of that principle perhaps isn't too surprising.
Though I'm not sure that the framers, with their heightened sense of state sovereignty, would have thought that the Constitution enshrined that principle to the degree currently interpreted.
Regardless, that's where we are. The upside is that as long as you can find a state that lets you do what you want, you're free to go -- or ship your stuff -- there.
Which is also the downside.