[shawndrost]

Thank you for providing your expertise in this comment section. A few followup questions, if you will...

1. Posit for a second that 1970s lawmakers did intend to delegate sweeping powers to the EPA under the CAA and allow it to regulate CO2 in ways that reshaped the every sector of the economy, when the time comes. MQD says the CAA as-written didn't accomplish that, regardless of what legislators wanted, because the EPA can't decide major questions except where legislators clearly scope and delegate that authority. True?

2. Posit that a supermajority of lawmakers, today, wanted to rewrite the CAA to actually delegate those sweeping powers of CO2 regulation to the EPA. This would be impossible, because it's not possible to enumerate all the major questions, and clearly scope and delegate the necessary authority, in order to free the EPA's hand across future decades of rulemaking impacting every major industry. True?

3. My sense is that the 2012 EPA rules mostly killed new coal plants and doomed existing facilities, practically accomplishing the same kind of "generation shifting" described in your brief. This seems like the kind of "major question" that you argue cannot be decided by EPA rulemaking. Though any number of legal and practical facts may shield those 2012 rules from post-hoc scrutiny, similar rulemakings today would probably not pass muster. True?

4. What (if any) defensible actions do you think the EPA could take, today, to reduce CO2 emissions under authorities granted by 111(d) of the Clean Air Act?

Again, thanks for your 2c.

[andrewmg]

I don't think your second point is correct. Congress could most certainly empower EPA to administer a cap-and-trade scheme or even some kind of phase-out, as it did with (respectively) acid-rain precursors and CFCs. Congress could do the same for GHG emissions, without spelling out the impact on each and every affected industry or source. Congress might, for example, set an economy-wide emissions cap, set a schedule of annual caps or a formula, specify how EPA should go about determining the cap each year, or some combination of those things. If Congress specifies that all sources economy-wide (or some subset of them) will be subject to a cap, then it has answered the major question.

On your third point, see the paragraph on page 38 of my brief linked above. "Generation-shifting," as used in the CPP, was EPA's claim that it could set "achievable" emissions standards based on turning off a source. One can argue about whether new-source standards satisfy the statutory test (BACT) applicable to major industrial facilities and whether the agency's decision to set those standards at a particular level is supported by the evidence or otherwise arbitrary and capricious. But that's an entirely different inquiry from whether Congress empowered EPA to switch off more or less every source of emissions in the country as it so chooses.