The NAACP and the Southern Environmental Law Center say xAI installed and ran dozens of natural gas turbines at its second Colossus data center without the permits the Clean Air Act requires. The facility is in Southaven, Mississippi.
Their civil suit puts the yearly emissions at 1,700 tons of nitrogen oxides, 180 tons of particulate matter, 500 tons of carbon monoxide and 19 tons of formaldehyde. A separate class action from Southaven residents followed, over the constant noise from the site.
The Justice Department steps in
Then the federal government moved to end the case. In a memorandum from Associate Attorney General Stanley Woodard Jr., the Justice Department asked to intervene and to dismiss the suit under Rule 41 of the Federal Rules of Civil Procedure. According to an analysis in the Columbia Undergraduate Law Review, the department argued that xAI and its Grok system are indispensable to national security, citing the Iran war and U.S. leadership in AI, and that this outweighs the Act’s emission limits and construction permit rules.
The department did not dispute that xAI broke the law. Its argument rests on two points: the Clean Air Act gives the United States an unconditional right to join citizen suits at any time, and Rule 41(a)(1) lets a plaintiff dismiss a case before the defendant files an answer or a motion for summary judgment. By intervening, the government becomes that plaintiff.
The law review author calls that a misuse of the rule. Citizen suits exist to enforce the statute when the government cannot or will not, the article argues, and when Washington does intervene it normally does so to carry the case on. If the motion succeeds, the author warns, citizen suits as a tool for holding companies to environmental law would be at risk.
What the filing says about the site
The Mississippi plan under the Clean Air Act requires permits for new stationary sources of pollution and compliance with emission limits. Colossus 2, the suit says, never got the permits, even though its turbines run well past regulatory thresholds. Six public schools are within walking distance.
The first Colossus facility is cited as a pattern. During its construction xAI said only fifteen turbines were running, while aerial imagery later pointed to about thirty-five. xAI argued temporary turbines did not need permits, but the EPA’s New Source Performance Standard, released January 9, says permits are required even for temporary construction. The NAACP filed suit on April 14.
Why the stakes extend past Mississippi
The article notes that data centers now use 5-6% of American electricity generation, and that the emissions from powering them are estimated to cause roughly $25 billion in damage each year.
Public opinion has also moved. A Heatmap poll found 43 percent of people would support a data center near them and 42 percent opposed in August 2025. Now only 21 percent support one and 71 percent are against.
