U.S. Supreme Court on Monday declined to hear an appeal from two Iowa counties seeking to enforce local regulations on a proposed carbon sequestration pipeline, leaving in place a lower court ruling that federal law takes precedence over local ordinances.

Story and Shelby counties had requested a review after the U.S. Court of Appeals for the Eighth Circuit ruled that their local safety standards were preempted by federal pipeline regulations. 

The legal battle began in 2022 after county supervisors enacted ordinances establishing setback distances, permitting requirements, and emergency management standards for hazardous materials pipelines.

Summit Carbon Solutions, the Iowa-based company behind the multi-state project, sued the counties later that year, and the federal courts consistently sided with the company.

The courts asserted that local governments cannot interfere with federal safety standards or pipeline routing decisions made at the state level.

In a statement on Monday, the Shelby County Board of Supervisors expressed disappointment, stating the case was a vital effort to protect "local control authority." 

However, the Supreme Court did not offer an explanation for its denial, which was listed among dozens of other rejected cases. 

While Summit Carbon Solutions declined to comment on the decision, Tom Buis, CEO of the American Carbon Alliance, said the move allows "important progress to continue." 

Buis argued that carbon capture technology is essential for keeping the ethanol industry competitive and creating new markets for farmers.

The focus now shifts to the Iowa Legislature, where the debate over eminent domain continues. 

An Iowa House Judiciary subcommittee is scheduled to meet Tuesday afternoon to discuss House Study Bill 507, which proposes a ban on the use of eminent domain for carbon pipelines. 

Landowners opposing the project, many from Shelby County, are expected to lobby at the Iowa State Capitol to voice their concerns.