The oral arguments will take place Monday with just eight justices, as conservative Justice Samuel Alito announced last week that he would step aside. He did not say why; liberal groups have said for months that he should recuse himself because he owns stocks in other oil companies that could benefit from a ruling in favor of Exxon and Suncor. Alito’s decision was a surprise, as the court had told NBC News in May there was no need for him to step aside.

The absence of one member of the court’s conservative majority is viewed as a blow to the oil companies, as his vote might have been crucial. It also raises the possibility of a 4-4 split that would leave the big legal issues unresolved and allow the Colorado lawsuit to move forward.

“Obviously that wasn’t welcome news from our perspective,” Michael Williams, West Virginia’s solicitor general, said of Alito’s recusal at a briefing last week. His state joined a brief backing the oil companies.

The companies have two main arguments. The broader argument is that under the Constitution, states simply do not have the authority to do anything related to greenhouse gas emissions because they would effectively be regulating outside their own borders. Only the federal government can set policy in inherently nationwide issues that also have foreign policy implications, the lawyers said in court papers.

“Because air and water are shared natural resources that flow without concern for political borders, the States each have their own potentially conflicting interests. By joining the Union, the States surrendered their right to resolve those conflicts by resorting to their own law in lieu of a neutral, uniform federal law,” the lawyers wrote.

Second, the companies say such lawsuits are trumped by the federal Clean Air Act, which regulates air pollution.

Boulder’s lawyers countered in court papers that state courts have long handled cases on issues that have nationwide impacts, such as product liability. They also pointed out that the lawsuit does not seek to cap any emissions in Colorado and that it is focused solely on the allegation of consumer deception, the type of issue state courts routinely address.

“That exercise of traditional state power has never been thought unconstitutional,” they wrote.

The litigation is playing out amid a broader battle between oil companies and their allies on one side and groups advocating for action on climate change on the other.