The U.S. Department of Justice notified the U.S. District Court in Denver that it is considering filing a Statement of Interest in a lawsuit challenging Colorado’s and Denver’s building energy performance standards on federal preemption grounds.

The notice says the federal government has questions about the preemptive scope of the Energy Policy and Conservation Act that sets national efficiency standards for appliances and equipment and generally bars states and localities from imposing conflicting requirements.

“As the United States has explained in other recent cases, ensuring the utility of nationally applicable standards adopted by the Department and preempting state and local regulations that would undermine those standards both upholds EPCA’s broad preemption provision and advances the Department’s administration of the statutory scheme,” the notice said.

Government offices were closed Friday for the Juneteenth holiday.