Have you read Bleak House by Charles Dickens? Me neither — it’s very long — but I did watch the miniseries. The plot involves a lawsuit over an inheritance, Jarndyce v. Jarndyce, which drags on for so many years that, in the end, there’s nothing left to inherit: The entire estate has been spent on legal fees.

I think of that miniseries each time I learn of a new twist in the longstanding legal battle over EPA restrictions on mercury pollution from power plants. And I worry that, like Jarndyce v. Jarndyce, the mercury litigation could carry on long past the point of futility.

It’s already been almost 17 years since the EPA first concluded that it should issue a rule limiting mercury emissions from coal- and oil-fired power plants. It’s been more than five years since the agency actually did issue such a rule. And it’s been more than two years since the nation’s power plants started complying with the rule. All along the way, the EPA, states, power companies, and public health and environmental groups have been fighting about the rule in court. They show no signs of stopping anytime soon.

Not long ago, I could have painted a rosier picture. A hearing on the latest iteration of the case was set for May 18, and an optimistic wonk could imagine that, by next winter, the D.C. Circuit Court of Appeals would issue a decision siding with the EPA and, by the following summer, the Supreme Court would decline to hear an appeal, thus ending the mercury dispute for good.

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Unfortunately, the Trump administration had other plans. Two weeks ago, President Trump’s recently installed EPA administrator, Scott Pruitt, asked the D.C. Circuit to put the case on hold while the agency reconsiders whether regulating mercury is such a good idea. And last Thursday, over the objections of the states and nonprofits that support the rule, the D.C. Circuit granted the agency’s request.

It bears repeating here that the rule in question was finalized over five years ago. Excuse me while I scream into the wind for a moment.

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Where we’ve been

OK, I’m back. Before we turn to the mercury rule’s uncertain future, let’s take a quick(ish) tour of its tortured past:

In 1990, Congress added a list of 189 “hazardous air pollutants” to the Clean Air Act, including mercury and a variety of toxic substances that were known or suspected to cause cancer or other serious health effects, like birth defects. For most industrial sources of these pollutants, the EPA was required to set strict emission limits as quickly as possible. But, for reasons that we don’t need to get into here, Congress treated power plants differently: It instructed the EPA to undertake a study of the health risks posed by power plants’ emissions of the listed pollutants and to determine, in light of the study results, whether regulating such emissions was “appropriate and necessary.” Under the law, the EPA had three years to complete the study.

In 1993, the EPA did not complete the study.

In 1994, the EPA did not complete the study.

In 1995 … you get the idea.

In 1998, the EPA completed the study! It found that, of the “hazardous air pollutants” emitted by power plants, mercury from coal- and oil-fired plants was of greatest concern because it could damage the developing brains of fetuses and young children. (Natural gas–fired plants emit virtually no mercury.)

In 2000, in the closing days of President Bill Clinton’s second term, the EPA formally determined that regulating mercury emissions from power plants was “appropriate and necessary.”

In 2005, the George W. Bush-era EPA attempted to retract that “appropriate and necessary” finding. (The Bush administration still planned to limit power plants’ mercury emissions, but it wanted to do so in a far less stringent fashion than the Clean Air Act required under the “hazardous air pollutant” program.)

In 2008, the D.C. Circuit found that the Bush EPA’s reasons for retracting the Clinton EPA’s “appropriate and necessary” finding didn’t pass muster under the Clean Air Act.

In 2012, the EPA, now run by an Obama appointee, reaffirmed the Clinton-era “appropriate and necessary” finding and issued the Mercury and Air Toxics Standards, which at last set strict limits on power plants’ emissions of mercury, as well as other heavy metals like arsenic and nickel, and “acid gases” like hydrochloric and hydrofluoric acid.

In 2015, a five-justice majority of the Supreme Court held that the EPA’s “appropriate and necessary” finding was invalid because the agency hadn’t considered the costs of regulation when making the determination. To be clear, the agency hadn’t ignored costs altogether. It had, in fact, performed an extensive cost-benefit analysis and found that the mercury rule’s annual benefits would outweigh its annual costs by tens of billions of dollars. But the EPA had waited to perform this analysis until the second stage of its regulatory process, when it determined how stringently power plants’ mercury emissions should be regulated, as opposed to the first stage, when it determined whether those emissions should be regulated at all. And in the eyes of a slim majority of the Supreme Court, that timing mattered. Even so, the mercury rule wasn’t struck down altogether. Instead, the courts left it in place while EPA reevaluated its “appropriate and necessary” finding with costs in mind.

In April 2016, EPA issued a “supplemental finding” concluding that, even with costs taken into account, regulating mercury and other toxic emissions from power plants was still “appropriate and necessary.” That supplemental finding was promptly challenged in the D.C. Circuit by some of the same states and industry groups that had sued to block the mercury rule the first time around. Because they could no longer claim that EPA didn’t consider costs at all when making its finding, the challengers now objected to the manner in which the agency weighed those costs against regulatory benefits. The D.C. Circuit was set to consider these objections to the agency’s analysis at the now-canceled May 18 hearing.

(Disclosure: My employer, the Institute for Policy Integrity at New York University School of Law, has, over the years, filed three “friend of the court” briefs in support of the mercury rule, one of which I coauthored.)

Where we’re going

So what happens now? Well, the EPA could try to retract its “appropriate and necessary” finding, just as the Bush administration did in 2005. That would require the agency to go back through the same lengthy public comment process that it used to make the finding in the first place. Once finalized, the retraction would almost certainly be challenged in court by states and public health and environmental organizations, just as the Bush retraction was.

That skirmish could easily extend beyond the 2020 election, meaning that, before it’s fully resolved, a new administration could decide to retract the Trump EPA’s retraction of the Obama EPA’s finding. And then that decision would be litigated. And then a subsequent administration could decide to retract the retraction of the retraction. And maybe a couple hundred years from now, when we’re all living on starships powered by dilithium crystals, a handful of lawyers will gather in the judicial holodeck once a week to debate whether, back in 2012, it was “appropriate and necessary” for the EPA to regulate mercury emissions from the coal- and oil-fired power plants that no longer exist on the planet we no longer inhabit.

Why it matters

Seriously, though, is there a point to any of this? As I mentioned earlier, the mercury rule has already been implemented. All of the power plants it covers have already either installed the control technology necessary to comply with the rule or, in cases where that didn’t make economic sense, shut down altogether. Even if the rule is ultimately struck down, updated plants aren’t going to dismantle their expensive new emission controls and retired plants aren’t going to come back online. Doesn’t that mean we’re already in Bleak House territory, futility-wise?

Not just yet. There are two reasons this fight still matters. The first is fairly simple: Installing emission-control technology isn’t the same as using emission-control technology. It’s likely that, in the absence of the mercury rule, some plants would run their new equipment less often to save on operating costs and, as a result, pollute more.

The second reason is wonkier, but likely more important to public health in the long term: Some of the methodological questions the mercury litigation raises about cost-benefit analysis have important implications for future environmental policy. For example, the mercury rule’s opponents have challenged the EPA’s consideration of a number of real but unquantified benefits of mercury reduction, such as the avoidance of various cognitive impairments associated with mercury exposure. Opponents have also challenged the EPA’s consideration of indirect benefits of the mercury rule — primarily, reductions in particulate matter pollution that occurred as a happy side effect of the steps plant owners took to control their mercury emissions.

For decades, under administrations of both parties, the EPA has taken difficult-to-quantify and indirect regulatory benefits into account when crafting pollution restrictions. Doing so is consistent with longstanding White House guidance, past court decisions, and the advice of prominent economic scholars. Even so, the Trump administration might conclude that its deregulatory goals are better served by ignoring such benefits. After all, it’s much easier for the White House to characterize repealing a bunch of environmental rules as socially beneficial if it systematically discounts much of the good those rules do for society.

Accordingly, if the EPA tries to justify a repeal of the mercury rule by arguing that the agency is legally precluded from considering unquantified or indirect benefits when determining whether a regulation is “appropriate and necessary,” it will be important for states and nonprofit groups to push back hard. A court’s acceptance of such a cramped interpretation of the EPA’s legal authority would not merely imperil the mercury rule, but also could constrain a future administration’s ability to issue strong environmental protections.

And so, interminable as it sometimes seems, the fight over mercury regulation should — and no doubt will — continue. Who knows? It might make for a great miniseries someday. (OK, probably not.)