You may have heard that the U.S. Supreme Court has agreed to hear several cases that challenge the Environmental Protection Agency’s methods for regulating greenhouse gases. But there is another case currently being reviewed by the high court that could be far more damaging to the federal government’s ability to address climate change. You wouldn’t know that it was an environmental case from looking at its name, McCutcheon v. Federal Election Commission, but it has high stakes for anyone concerned about millionaires and billionaires from fossil fuel businesses using their ill-gotten riches to influence politics.

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McCutcheon, which was heard before the Supreme Court on Oct. 8, is about melting caps — but not those of the glacial variety, vanishing due to climate change. It’s about melting away the legal caps that limit the amount of money individual donors can give to candidates, political parties, and political action committees.

The case, brought by Shaun McCutcheon, the millionaire owner of an Alabama coal mining and engineering business, has been called the sequel to Citizens United, the 2010 U.S. Supreme Court ruling that granted corporations “personhood” and allowed super PACS to spend unlimited amounts of money on elections. In the 2012 campaign, the ruling opened the floodgates to over $933 million in new campaign contributions, most of which funded attack ads.

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Now along comes McCutcheon, wanting to inject even more money into politics. The groups opposing McCutcheon, which include the NAACP and the New York City-based think tank Demos, argue that the more money wealthy citizens can contribute to elections, the less electoral power the votes of people of average or low means will have, since they can’t match the dollar spread.

But environmental groups like Sierra Club and Greenpeace are fighting McCutcheon, too. They signed on to an amicus brief arguing against the coal millionaire, and have staged rallies across the nation, alongside civil rights and social service groups, to mobilize citizens against his agenda.

In addition to coal mining and engineering, McCutcheon’s Coalmont Electrical Development Company addresses “complex regulations” from government that smaller extraction companies can’t or don’t want to handle, according to its website. Given that the EPA just issued tough regulations on new coal plants and is preparing regulations for existing ones, McCutcheon’s company is either about to get a whole bunch of new clients, or he’s out to dismantle the regulations altogether. Judging from his case before the Supreme Court, it appears he’s going for the latter.

It will probably come as no surprise that McCutcheon is a rabid climate denier. You can check out some of his tweets in this post from Kate Sheppard at Huffington Post.

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So what, exactly, is he trying to do? Right now, federal law says that an individual can only donate a maximum of $2,600 per candidate, per election season (one during primary, one during general) in federal elections. You can give to multiple candidates, but once you hit $48,600 in total gifts, you can’t donate any more to candidates that year (though if you’ve got more cash burning a hole in your pocket, you can give another $80,000 or so directly to political parties and political action committees).

McCutcheon’s lawsuit aims to lift those limits so that he can pay out his $2,600 max to as many candidates as he wants to.

The Center for Responsive Politics reports that a “tiny elite” of only 241,000 people gave over $2,500 in the 2012 election cycle — that’s out of an estimated 310 million voters, or about 0.08 percent of the population.

“There are only a handful of people who are trying to find ways to build more power and make more profit off of what they’re doing,” says Courtney Hight, director of Sierra Club’s democracy program. “It’s changing the political system, and it affects us not only as environmentalists, but also as citizens of this country.”

The outlook for the McCutcheon ruling, which could come as late as next summer, doesn’t look bright, according to analysts. This is, after all, the same Supreme Court that delivered the Citizens United ruling. And even if the court rules in favor of the government, efforts to get more money into politics will continue in Congress, where Republican Sen. Mitch McConnell, another climate denier, has also been pushing for the elimination of political contribution limits.

But the resistance will continue as well. It’s not just McCutcheon these groups are fighting, but all of the other McCutcheons out there — people who would be allowed to shell out millions of dollars for candidates who want to stop the federal government from regulating greenhouse gas emissions.

“The American public demands clean air, clean water, and action on climate change,” Greenpeace Executive Director Phil Radford said on a press call shortly before the court heard the McCutcheon case. But thanks to what he called a “legalized system of corruption through money in politics” very few major environmental laws have passed in the U.S. since 1980.

Hight says her group’s involvement in McCutcheon is part of a broader effort to stand up against polluter industries and those who wish to corrupt politics with money — often the same people, she points out. This summer, the Sierra Club asked members to write their congressional representatives to voice their disapproval of the U.S. Supreme Court’s decision to gut a key provision of the Voting Rights Act.

“These are the people we’ve been fighting for a long time,” says Hight. “As they put more money into elections they are also funding attacks on voting rights in the states. So they’re pumping money into [candidates who support fossil fuel industries] and then also trying to stop us from having a voice at the polls.”