This morning, the Supreme Court decided against EPA in a case concerning the agency's regulations on mercury pollution. Brad Plumer has a great explainer on the background and details. I just want to highlight one aspect of the ruling that hasn't gotten enough attention in all the coverage, namely: it is likely pointless.

The ruling is probably not going to change the mercury regulations. It's probably not going to have any effect on the power sector. It probably won't establish any significant legal precedents. The most likely outcome of the ruling is ... nothing much.

The ruling amounts to Scalia poking his thumb in EPA's eye, to no particular effect.

The rule establishes no significant legal precedent

The Clean Air Act has a section regarding the regulation of hazardous air pollutants (HAPs, which include mercury). That section instructs EPA to regulate HAPs if they are deemed a threat to public health and pollution controls are available. Costs are not mentioned and EPA has chosen not to take costs into account when deciding whether to regulate HAPs. (Costs are taken into account at a later stage, when the regulations are being written.)

The CAA also has a subsection specifically addressing HAPs from power plants. After establishing regulations for other sources, EPA is instructed to consider whether further regulations of HAPS from power plants are "appropriate and necessary."

EPA chose to use the same basic procedure on power plant HAPS that it had for other sources: when deciding whether to regulate, it considered only public health and the availability of pollution controls. Costs entered the process later, when the agency was writing the regulations.

Scalia's ruling says that this is an unreasonable interpretation of "appropriate and necessary." It says that the CAA treats power plants as a unique category for a reason and that "appropriate" must be interpreted to include cost considerations, not just when writing the regulations but when deciding whether to regulate.

Putting aside the merits of the ruling, it's simply not going to matter much, legally speaking, for three reasons:

The ruling only applies to the specific subsection of the CAA devoted to HAPs from power plants. Once EPA has regulated those pollutants, that subsection will effectively become vestigial; EPA will have no need to use it again. So this ruling is a one-off judgment addressing a one-off regulation. It won't affect how future EPA regulations are developed. The court could have used this case to substantially rein in Chevron deference. (The court found, in the famous Chevron vs. NRDC case, that when statutory language is ambiguous, the court should give executive agencies wide latitude in how to interpret it; the ruling only specifies that the interpretation must be "reasonable.") In his concurrence — which, notably, none of the other eight justices joined — Justice Clarence Thomas ranted and raved about Chevron deference and how it violates the Constitution and corrupts our bodily fluids. But in his ruling, Scalia notably didn't taken on Chevron. Instead, he judged the agency's interpretation of the statute unreasonable. That leaves the basic principle of Chevron deference untouched. Even more radically, the court could have taken up an issue that the Chamber of Commerce urged upon it, namely the role of "co-benefits" in EPA's cost-benefit calculations. The vast bulk of the benefits of restricting HAPs from power plants come not from the decline in HAPs themselves, but from the decline in particulate pollution that will accompany those controls. If those co-benefits are included, the benefits of HAPs regulations wildly outweigh the costs. If they are not, the costs exceed the benefits (at least as currently calculated). The Chamber wanted the court to rule the inclusion of co-benefits out-of-bounds, which would have had enormous (and deleterious) effects on future air-quality regulations. But Scalia notably did not address that question. He makes clear in passing that he is suspicious of co-benefits (which he calls "ancillary benefits"), but he makes a point of emphasizing that nothing in the ruling instructs the agency how to take costs into consideration, only that it must. Until explicitly instructed otherwise by a court, EPA can and will continue taking co-benefits into consideration.

The power sector has already complied with mercury regulations

As Brad notes, linking to this excellent SNL analysis, most power plants have already installed the controls necessary to comply with the mercury and air toxics (MATS) regulations. There are only a few exceptions. Here's the money quote from SNL:

... 200 plants, comprising about 20% of U.S. power capacity, were given up to an extra year to comply with the MATS, mostly in order to finish installing mercury controls. Of those, 22 plants, representing less than 1% of U.S. power capacity and 1% of U.S. energy production in 2013, remained in operation without MATS controls to provide grid reliability. It is just these 22 plants, along with perhaps a few others, that the court could save from retirement by striking down the rule. "It is fair to say that MATS has already largely done what it's going to do," said Jeff Holmstead, an industry attorney for Bracewell & Giuliani.

That's the only thing at stake here: how long these 22 plants get to keep spewing HAPs. That's not nothing — especially to the vulnerable populations exposed to those toxic pollutants — but it amounts to a mopping-up operation.

You might note an irony here. The entire Supreme Court case is premised on the fact that MATS regulations are "the most expensive ever." Industry claims it's outrageous that EPA didn't consider these extraordinary costs, which it says could cause blackouts and destroy the power sector and leave the US a smoking ruin.

Oh, but, by the way, while we were debating this, the power sector went ahead and complied with the regulations. Notice any blackouts? Any big bankruptcies in the power sector? Any economic devastation? No. As usual with air pollution rules, when the power sector quits complaining and starts complying, the costs turn out to be much lower than anyone anticipated. This case was a fight over a question that's already been settled by facts on the ground.

The rule is likely to remain in place, unchanged

The ruling does not, contra most media coverage, "strike down" the rule. It remands the issue back to the same panel on the DC Circuit Court that previously upheld the rule by a 2-1 ruling (it was the absurd dissent in that case that led SCOTUS to take up the case in the first place). That panel, as evidenced by its original ruling, is broadly friendly to EPA.

The DC Circuit Court will have to decide how to proceed. It could declare the rule void and force EPA to start over, which would cast the power sector into chaos and almost certainly bump the completion of the rule back past the end of Obama's presidency, opening at least the possibility that a Republican will be elected in 2016 and decide to sabotage the whole process (like Bush tried so hard to do in the late 2000s).

But that seems unlikely, given the narrowness of the ruling and the DC Circuit's general sympathy for EPA. More likely, it will keep the rule in place while EPA completes a cost-benefit analysis, per Scalia's insistence.

If that's the court's decision, then EPA will run a cost-benefit analysis — using co-benefits — and determine that, lo and behold, MATS regulations are appropriate and necessary! That won't take long, as all the evidence is already on the record. Potentially, it could be done in six months to a year, fast enough that it will be resolved while Obama is president. Then the rule will remain in place, unchanged.

Scalia's scream therapy

Long story short: while there a possibility that this ruling could substantially delay MATS regulations, the mostly likely outcome is ... nothing. The regulations will stay in place, the power sector will finish the work of compliance, and no particular legal precedents will be established.

Given all that, it's difficult to see what motivates Scalia's ruling other than pique. It's a chance to smack EPA around a little. Perhaps it made him feel better about losing the same-sex marriage battle.

But the work of preventing mercury from poisoning pregnant women and unborn children will proceed apace.