The Supreme Court, by way of a 5-4 decision on Monday, sent back US Environmental Protection Agency (EPA) rules limiting mercury and other pollutants generated by fossil fuel-fired power plants to the DC Circuit Court of Appeals for further deliberation.
They did not, however, suspend the Mercury and Air Toxic Standards, commonly referred to as MATS, which "remain in place," an EPA spokesman confirmed to VICE News. The agency noted in a press release that "the decision was about how and when the Agency considered costs, not EPA's Clean Air Act authority to limit hazardous air pollutants."
Power plants are the number one source of mercury emissions, linked to respiratory illnesses and birth defects, in the United States. The EPA said the regulations, which applied to roughly 600 plants, would cut mercury pollution by up to 90 percent, and also limit lead and arsenic spewing from the plants.
But several environmental lawyers said the ruling left the EPA's limits not in peril, but simply needing more work.
"The decision does not strike down or block these protections," Neil Gormley, a Washington DC-based attorney with Earthjustice told VICE News. "The Supreme Court didn't address what the real world remedy ought to be. It identified a narrow flaw in the EPA rule and gave the agency another hoop to jump through."
That hoop is costs. The court ruled in favor of a coalition of industry groups and 20 states, which argued that the agency failed to consider the costs the industry would incur when implementing the new pollution regulations.
Watch the VICE News Documentary, "Toxic Waste in the US: Coal Ash"
Environmental groups estimated the pollution limits could prevent 4,200 to 11,000 premature deaths each year and provide up to $9 in health benefits for each dollar spent on limiting power plant pollution.
Since MATS went into effect in April, many plants have already upgraded their facilities. At least half of all coal-fired capacity was in compliance as of April 1, according to an SNL Financial analysis, and as few as 22 plants, responsible for less than 1 percent of US energy production in 2013, would avoid retirement because of the court's ruling, according to separate analysis.
"The vast majority of power plants have already installed the technology they need to control this pollution and, as we can see, the sky didn't fall," Gormley told VICE News. "What can get lost in all legal technicalities is how desperately needed these protections are. This rule is already delivering huge benefits in terms of public health and the environment."
The biggest questions that remain are whether the DC circuit judges will vacate the rule limiting emissions or leave it in place while the EPA responds to the Supreme Court's ruling and what methods the agency will use to calculate the cost on power plant operators of implementing the regulations.
"Notably in its decision, the court was not very prescriptive," Graham McCahan, senior attorney with the Environmental Defense Fund, told VICE News. "They gave EPA a wide latitude of how it might consider costs."
McCahan pointed to a 2008 case, North Carolina v. Environmental Protection Agency, for possible precedent toward keeping the regulations. There, the DC Circuit Court vacated an EPA rule governing drifting emissions, sending the regulation — which had already taken effect — into similar legal limbo. And while the court said the rule suffered from "more than several fatal flaws," it protected the limits while the EPA hammered out a fix, because the regulation "had become so intertwined" that getting rid of it " would sacrifice clear benefits to public health and the environment."
"They said we're going to leave this flawed rule in place because, and this is the important part, we need to preserve the environmental benefits of the rule," McCahan told VICE News. "That's an important piece to answer the question of whether the rule will get vacated during remanding."
Monday's verdict prompted reactions from organizations like the American Lung Association, which noted that limiting the pollutants would have prevented 130,000 childhood asthma attacks a year. They demanded "no further gap in protections that have been overdue by more than 20 years already."
Others promised the battle wasn't over.
"The court's decision to let polluters off the hook is a huge setback for our kids' health," said Environment New York's Director Heather Leibowitz. "But we'll keep fighting for clean air and a healthier future. Polluters' days of dumping unlimited deadly toxins into our air are numbered."
Oklahoma Senator James Inhofe, chairman of the Senate Environment and Public Works (EPW) Committee, who denies man-made climate change, called the ruling a "much-needed win for American businesses and families."
"I applaud the court's decision to put a halt to reckless rule making that does not take into account commonsense considerations, such as cost," Inhofe said."This serves as a reminder that the agency should be implementing laws written by Congress, instead of rewriting those laws to fit the president's extreme environmental agenda."
Scott Segal, Director of the Electric Reliability Coordinating Council, a coalition of energy companies, cheered the ruling.
"As children, we learn that every day can't be Christmas. EPA just learned that today. The agency cannot continue to write rules without regard to their cost, simply because the agency believes its cause is just," Segal said in a statement. "These considerations should serve as important warnings to consider cost and reliability in a thorough manner before it finalizes its carbon rules. Failure to do so will place legacy before legality."
Follow Darren Ankrom on Twitter: @darrenankrom