After the Environmental Protection Agency announced in December that it would not move forward on regulations for hardrock mines, six environmental groups took the agency to court last month, arguing that the decision could harm cleanups for mines throughout the U.S.

On Friday, 14 states, including Nevada, entered the legal fray, filing a motion to intervene in the case over whether the environmental agency was meeting its congressional mandate to require financial assurances from mining operators to clean up pollution. The case is the latest in more than a decade of wrangling over the Comprehensive Environmental Response, Compensation and Liability Act, or CERCLA. In its decision last December, the EPA argued that the move would leave more power to states, like Nevada, which has bonding requirements for miners.

Attorney General Adam Laxalt, the Republican candidate for governor, said that Nevada and the other states, led by Arizona and New Mexico, sought to defend “the EPA’s deference.”

“The EPA’s deference to Nevada’s exiting regulations is a great example of cooperative federalism in action, which is why Nevada, along with so many other hardrock mining states, is intervening to defend the EPA’s imminently [sic] reasonable decision,” Laxalt said in a statement.

But the groups pushing back against the EPA, including the Sierra Club and Nevada-based Great Basin Resource Watch, said the agency’s decision, under the leadership of EPA Director Scott Pruitt, was a blow to strengthen the requirements to clean up mines across the West.

John Hadder, who directs Great Basin Resource Watch, said his organization has been engaged on the issue for nearly two decades and thought it was making progress during the Obama administration. In December 2016, as President Barack Obama was leaving office, the EPA issued a draft rule on hardrock mines, which includes operations that produce metals such as iron, copper and lead. The agency received about 11,000 comments on the draft regulation.

One year later, Pruitt announced the EPA would scrap the process and not issue a final rule, saying the agency was now “confident that modern industry practices, along with existing state and federal requirements address risks from operating hardrock mining facilities.”

“It’s frustrating to get that far,” Hadder said. “And he just throws it out.”

Elected officials, including Gov. Brian Sandoval and Sen. Dean Heller, applauded the move last December, according to the Elko Daily Free Press. Heller said it was a “win for Nevada’s mining industry” and Sandoval said it recognized “the reality that the states have been capably regulating mine bonding without interference from Washington and should be allowed to continue to do so.”

Nevada, through its Division of Environmental Protection, regulates mine reclamation and requires upfront financial assurances from companies in case they go bankrupt. Nevada currently has about $2.8 billion in these assurances, according to the filing from the states.

But Hadder argued that there are loopholes and exemptions to the state law that the federal rule would have fixed. Hadder pushed back on the argument that the federal rules would have been duplicative of state law, noting that the regulation provided for loosening financial requirements in cases where companies were already required to comply with stronger state statutes.

The states addressed this point in their motion to intervene, filed on Friday.

“EPA stated that it did not intend to preempt state financial responsibility but admitted that “[i]t is the courts that would make any final determinations about the preemptive effect of CERCLA 108(b) regulations at any particular facility,” the attorneys general write in their filing.

In addition to Nevada, Alaska, Arizona, Arkansas, Colorado, Louisiana, Michigan, Montana, New Mexico, Utah, South Carolina, South Dakota, Wisconsin and Wyoming signed the filing. Industry groups, including the National Mining Association, are also looking to intervene.

Now all of the parties find themselves back where they started — in court

A lawsuit is what prompted the Obama administration to open a rulemaking process in the first place. In 2009, a federal court ruled the EPA must promulgate rules on whether to get financial assurances from miners under CERCLA, the 1980 law that created the federal “Superfund.”

That process ended with Pruitt’s decision in 2017 to scrap the draft regulation. The states, like Pruitt, also want to maintain the status quo. The worry from the perspective of these states, according to the motion to intervene, is that the federal regulations could supersede state requirements, potentially putting their existing bonding programs at risk.

“if EPA were to require financial responsibility for active hardrock mining operations under CERCLA 108(b), EPA would put at risk billions of dollars in financial responsibility already in place under state laws,” the states argued in their filing. “Such a result would severely undermine the States’ mining regulatory programs, many of which have been in place for decades and are fully regulating active hardrock mining operations in those states.”

Earthjustice attorney Jan Hasselman, who is one of the lead attorneys on the case, said the state’s argument didn’t make sense. He argued that the Obama administration’s draft rule was crafted around state rules, and it still found federal regulations were necessary to prevent taxpayers from being on the hook for cleaning up mines where gaps existed in state law.

“The proposed rule was intended to work alongside state rules,” he said. “The EPA made specific findings that there were gaps that were not addressed by states and other agencies. The whole point of this was to close the gaps, not to preempt any [state] regulation.”

He said the Trump administration has done a “180-degree turnaround.” In not going through with a final rule, he argued that Pruitt was ignoring risks left by loopholes in state requirements.

“It was a 180-degree turnaround from the findings of the previous administration,” he said.