The background is pretty interesting. In 2007, the Court ratified the EPA's power under the Clean Air Act to regulate greenhouse gases as an "air pollutant" in the context of motor vehicles. But this created a bit of problem in another section of the Clean Air Act, which requires the EPA to regulate, by issuing permits, for major "stationary" emitters of "any air pollutant." The statute defines major permitters as those emitting more than 250 tons of an air pollutant in a year.
The problem is that tens of thousands of buildings, schools, malls, etc, emit that much in greenhouse gases, and thus would need to be permitted if that section applied. Everyone agreed that was not intended. To avoid that absurd result, the EPA issued a regulation setting a different, much higher, threshold for the emission of greenhouse gases (between 50,000 and 100,000 tons, depending on the circumstances).
Today, the Court struck down those regulations, finding that "air pollutant" in the context of the stationary emitters means something different than what it meant in the context of the Act-wide definition applicable in the motor vehicle case. Based on context, and prior regulations, the Court held that "air pollutant" means something much narrower in the relevant section of the act, since the broader definition would render it ridiculous. Justice Scalia had no problem finding the same term to mean different things in different parts of the same statute: "the presumption of consistent usage readily yields to context, and a statutory term—even one defined in the statute—may take on distinct characters from association with distinct statutory objects calling for different implementation strategies."
So the Court found that nothing in the statute compelled the EPA to treat greenhouse gases as "air pollutants" in this context. Next, it considered whether the EPA's interpretation that it was even allowed to regulate the stationary emitters because of their greenhouse gas emissions. Justice Scalia said no, for a variety of reasons. Most interesting me, though, was this:
EPA's interpretation is also unreasonable because it would bring about an enormous and transformative expansion in EPA's regulatory authority without clear congressional authorization. When an agency claims to discover in a long-extant statute an unheralded power to regulate "a significant portion of the American economy," we typically greet its announcement with a measure of skepticism. We expect Congress to speak clearly if it wishes to assign to an agency decisions of vast 'economic and political significance."... [I]t would be patently unreasonable—not to say outrageous—for EPA to insist on seizing expansive power that it admits the statute is not designed to to grant.Now, maybe it's just me, but I think Justice Scalia actually might have been thinking of the ridiculous argument for the trillion-dollar platinum coin here. Substitute "Treasury" for "EPA" and that is exactly what you'd see in any opinion considering the minting of a trillion-dollar platinum coin. There is no credible argument that Congress intended for the platinum coin statute to grant Treasury the last say on the nation's fiscal and monetary policies. It would be absolutely outrageous if Treasury pretended that it had such power.
Overall, this is another lesson in the vagaries of statutory interpretation. Just like "air pollutant" doesn't always means "air pollutant," the phrase "such denominations as the Secretary may prescribe" doesn't actually include a denomination with 12 zeros before the decimal point.
(By the way, this decision is not the end of the world. The Court held that the EPA had discretion to regulation the greenhouse gas emissions of those stationary emitters who were otherwise under the EPA's thumb based on their emissions of the narrower kind of "air pollutants." This gave the EPA pretty much every thing it wanted—despite the tweets of certain hacks to the contrary.)
This is Part 9 in The Gillette-Torvik Blog's 94-Part Series on the Trillion Dollar Platinum Coin idea