On October 30, 2026, U.S. District Judge Debra M. Brown denied X.AI Corp. and MZX Tech LLC’s motion to dismiss the NAACP’s lawsuit over gas turbines in Southaven, Mississippi. The ruling allows the claims to proceed; it leaves the question of whether the companies violated the law for later proceedings. Brown’s opinion and order explains why the court rejected the defendants’ argument that the turbines qualified as mobile sources exempt from permitting.
The case was brought by the NAACP and the Mississippi State Conference of the NAACP under the federal Clean Air Act and Mississippi’s State Implementation Plan, the state’s air-quality rules. A motion to dismiss asks a court to decide whether a complaint can proceed under the law. At this stage, Brown considered the complaint’s well-pleaded allegations as true; she did not conduct a trial on whether the alleged violations occurred.
The October 30 decision concerned the companies’ motion. A separate October 19 ruling allowed the U.S. Department of Justice to intervene but rejected its attempt to end the plaintiffs’ case. NeoTeo covered that earlier dispute.
Why the court rejected the mobile-source defense
Mississippi’s plan incorporates federal air-quality rules and their definitions of mobile sources. Those definitions cover motor vehicles, nonroad engines and nonroad vehicles. Brown concluded that, under the complaint’s allegations, the turbines did not fit those categories.
The complaint alleges that each turbine had heat input greater than 10 MMBtu per hour and that the turbines were not self-propelled or intended to move while operating. Brown treated them as stationary combustion turbines subject to Clean Air Act standards. Mounting a stationary turbine on a vehicle for portability did not make it a mobile source under the rules the court applied.
That conclusion allowed the permitting claims to proceed. It did not resolve whether the defendants ultimately violated permit requirements.
The state agency’s letter did not settle the issue
On July 29, 2025, the Mississippi Department of Environmental Quality told xAI that it understood the turbines would be on portable units and remain at the site for less than 12 months. The agency conditionally acknowledged an exemption on that understanding. Brown found that the letter gave the defendants fair notice of the agency’s view, but it did not bind the court or prevent the plaintiffs from arguing for a different interpretation.
Brown also rejected the defendants’ challenge to the NAACP’s right to sue under the Clean Air Act. She read the law’s “on his own behalf” language as allowing an association to sue to protect its members’ interests, while excluding class actions and suits on behalf of the public at large. The court separately rejected arguments that citizen suits violate Article II or the private nondelegation doctrine, reasoning that the plaintiffs seek to redress their own injuries rather than exercise the federal government’s enforcement power.
What the lawsuit alleges about the Southaven plant
The complaint alleges that X.AI Corp. and MZX Tech LLC constructed and operated the Colossus Gas Plant without permits required under federal and state law. It places the plant in Southaven, Mississippi, and says it supplies electricity to xAI’s Colossus 2 data center in Memphis, Tennessee.
The complaint identified at least 27 turbines at the plant as of April 7, 2026, with combined generating capacity of at least 495 megawatts. It estimated potential annual emissions from those turbines at about 1,700 tons of nitrogen oxides, 19 tons of formaldehyde, 580 tons of carbon monoxide and 180 tons of fine particulate matter. Those are the complaint’s estimates of potential emissions.
The NAACP and its Mississippi affiliate seek pollution controls and civil penalties of up to $124,426 per day per violation. Brown’s October 30 order allowed the claims to continue; the plaintiffs’ requested remedies remain part of the case.
