The trouble with air pollution is that it tends to travel — blowing downwind for hundreds of miles, entering the lungs of people living far from its source. Nitrogen oxides emitted by coal-fired power plants, for example, can waft across state lines and react with other chemicals in the atmosphere to form ozone, a potent pollutant and the main ingredient in smog. Last March, the federal Environmental Protection Agency issued a rule to rein in those downwind ozone pollutants in 23 states. But in the months since, states and fossil fuel industry groups have filed dozens of lawsuits to block the plan. As a result of this ongoing litigation, the agency’s ozone pollution reduction rule, dubbed the “Good Neighbor” plan, has been put on hold in 12 states, including Kentucky, Texas, and Utah. 

Those legal battles have now reached the Supreme Court. On Wednesday, as supporters of the rule demonstrated outside, attorneys representing the state of Ohio, the oil and gas pipeline company Kinder Morgan, the American Forest and Paper Association, and the manufacturing company U.S. Steel, among others, presented oral arguments before the Supreme Court. The groups want the court to grant what’s called an “emergency stay,” which would halt the Good Neighbor plan entirely — even in the 11 states already implementing the rule — while lawsuits in lower courts play out. 

The justices wouldn’t have a final say on the legitimacy of the EPA’s rule — that’s up to the U.S. Court of Appeals for the District of Columbia Circuit, which is currently wrangling with 18 related lawsuits on that question. But legal experts say that Wednesday’s oral arguments seem to indicate that the Supreme Court could end up wading into the validity of the Good Neighbor plan in its decision anyway, with untold public health consequences for residents of downwind states.

“The applicants are trying to get the Supreme Court to weigh in on the merits through this procedural stay application,” Zachary Fabish, senior attorney at the Sierra Club, told Grist based on what he heard at the court on Wednesday. “And the downwind folks in those states are paying the public health price.”

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A few justices commented on the plaintiffs’ unusual choice to argue in front of the Supreme Court before their pending litigation has been decided by the D.C. Circuit. The groups even admitted during oral arguments that they had requested a delayed briefing at the lower court so they could present their case to the Supreme Court first.

“It’s fairly extraordinary, I think, to be asking the court to decide this matter when you haven’t even lost below in terms of what is before the D.C. Circuit,” Justice Ketanji Brown Jackson told the plaintiffs. “So I’m trying to understand what the emergency is that warrants Supreme Court intervention at this point.”

That emergency, the state and industry plaintiffs argue, mostly boils down to the costs of complying with the EPA’s ozone reduction plan. In 2015, the EPA updated the federal air quality standard for ozone, which sets strict limits for that pollutant nationwide. According to federal law, each state was required to submit a plan within three years of the updated standard describing how it would reduce the amount of ozone pollution blowing downwind to other states. If they failed to do so, or submitted inadequate plans, the EPA was obligated under the Clean Air Act to enforce the Good Neighbor rule to reduce downwind pollution in those states. By February 2023, the EPA had rejected 21 states’ plans; another two, Pennsylvania and Virginia, did not submit one. 

In March, the agency issued the Good Neighbor plan for those 23 states, a rule that plaintiffs argued levies an unfair burden on states like Ohio and Indiana; oil and gas companies; and heavy industry. “In order to get into compliance with an unlawful federal rule, we are spending immense sums, both the states as well as our industries,” argued Ohio Deputy Solicitor General Mathura Sridharan. 

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But Judith Vale, a deputy solicitor general for New York who argued in favor of the Good Neighbor plan, noted that the EPA’s rule helps address inherent cost imbalances between upwind and downwind states. In many cases, power plants and industrial facilities in upwind states in the South and Midwest would simply need to turn on existing pollution controls to come into compliance. Downwind states like Connecticut and Wisconsin, on the other hand, need to reduce their own pollution while also compensating for pollutants blowing into their jurisdiction. 

Often, those states have “already exhausted a lot of the less expensive strategies,” Vale said. “So they need to turn to more and more expensive strategies to find any further cuts.”

While Jackson and other liberal justices seemed to question challenges against the Good Neighbor plan, conservative justices like Justice Brett Kavanaugh appeared more sympathetic. In response to a point raised by Malcolm Stewart, a deputy solicitor general at the U.S. Department of Justice, that pausing the air pollution plan would disproportionately harm downwind states, Kavanaugh agreed but added that “there’s also the equities of the upwind states and the industry,” concluding that both sides had experienced irreparable harm.

Fabish noted that the court’s decision to even schedule oral arguments for this case is highly unusual. The request for the emergency stay arrived on the Supreme Court’s “shadow docket,” a lineup of cases that, until recently, involved less consequential matters and got decided on without oral arguments, extensive hearings, or even explanations from the judges. But by asking for briefings and an oral argument, the court has created a kind of “process conundrum” for themselves, Fabish said. While the justices have some materials to base a judgment on, he noted they lack most of the evidence used in a typical case, such as extensive briefs, documents, and arguments. The justices also lack detailed opinions from a lower court, since the D.C. Circuit has yet to issue a decision.

All those factors, in addition to dozens of pending lawsuits related to the Good Neighbor rule in courts across the country, create a great deal of uncertainty around how and when the Supreme Court will rule on this application, Fabish said. Richard Lazarus, an environmental law professor at Harvard Law School, told Harvard Law Today that anywhere from four to six justices could agree to halt the rule, pointing to Kavanaugh, Neil Gorsuch, Clarence Thomas, and Samuel Alito as likely votes to do just that. Meanwhile, other justices worried aloud whether this case could encourage future plaintiffs to use the shadow docket as a venue to challenge environmental regulations. 

“I mean, surely, the Supreme Court’s emergency docket is not a viable alternative for every party that believes they have a meritorious claim against the government and doesn’t want to have to comply with a rule while they’re challenging it,” Justice Jackson said.