The Supreme Court grappled Tuesday with whether lawsuits under the Clean Air Act must be brought in Washington, where the Environmental Protection Agency is headquartered, or whether they can be brought in states where the specific issues often arise.

The cases involved national ozone standards and the EPA’s biofuel blending mandate, with the justices expected to settle disagreements among lower courts about their jurisdiction.

The Clean Air Act directs challenges to EPA action that have national implications to be filed in Washington, where they can be handled by the U.S. Circuit Court of Appeals for the District of Columbia. More regional disputes are to be filed locally.

Drawing those lines, however, has proved to be tricky for lower courts.

The cases come as the justices are dealing with broader questions about so-called “forum shopping,” where plaintiffs look to bring lawsuits in courts seen as more friendly toward their positions.

The practice has become commonplace for both conservative and liberal advocates looking to strike down or curtail policies pushed by political opponents.

Tuesday’s first case, EPA v. Calumet Shreveport Refining, involves small oil refineries’ challenge to the biofuel program.

The EPA had rejected several small oil refineries’ petitions to be exempt from the law’s requirements. Six of the refineries sought review of the decision in the 5th U.S. Circuit Court of Appeals, but the EPA asked that the cases be transferred to Washington.

The 5th Circuit declined.

The Justice Department said centralizing things in the D.C. Circuit will avoid inconsistent rulings across the country.

“Clearly, Congress wanted there to be a meaningful role for the D.C. Circuit,” said Malcolm L. Stewart, the Justice Department’s deputy solicitor general, defending the EPA. “The venue provision will work best if cases are routed to the D.C. Circuit.”

But Michael R. Huston, the lawyer for a refinery challenging the law, said the statute lays out how to determine if an oil refinery faces an economic hardship, and that analysis involves local factors.

“The important point for venue purposes — analyzing the evidence of local economic conditions facing small refiners in San Antonio and Shreveport — is a test that Congress assigned to the 5th Circuit, not the D.C. Circuit,” Mr. Huston said.

Two other cases heard Tuesday — PacifiCorp v. EPA and Oklahoma v. EPA —  involved challenges to the EPA’s disapproval of plans to meet national ozone standards.

States in the 4th, 5th, 6th and 8th circuits have been able to bring challenges in their respective jurisdictions.

However, the 10th U.S. Circuit Court of Appeals held that Utah and Oklahoma should have brought their challenges in Washington.

Mithun Mansinghani, representing Oklahoma, said state plans consider regional air concerns and should be weighed in the jurisdiction where the state is located.

“EPA made clear that interstate ozone transport is a regional scale pollution problem,” he said, noting the “regional effects” in his push to keep the legal conflict close to the state and out of Washington.

Justice Neil M. Gorsuch said pollution travels across the country and doesn’t “respect our jurisdictional boundaries.”

Still, he quizzed Mr. Mansinghani lightheartedly about what sort of a problem it is to have circuit splits if courts rule in different ways.

“We are going to have different interpretations of the statute with different circuits and all these terrible splits and gosh, we won’t have the immediate resolution in the D.C. Circuit that we could have,” he said.

“I don’t think splits are all that terrible,” Mr. Mansinghani shot back.

“Oh, really, we deal with them?” Justice Gorsuch said, which was met with laughter. The Supreme Court often takes disputes where circuit courts are split on an issue where the justices are forced to settle it.

Mr. Stewart, who also defended the EPA in this action, said he was troubled with the D.C. Circuit being painted as a hometown court for the EPA.

“If location in D.C. meant that the D.C. Circuit is a hometown court, then this court would be a hometown court for EPA and I have never had that perception,” he said, to which the justices laughed.

The disputes originally came to the court during the Biden administration. After President Trump won in November, his Justice Department looked to postpone the arguments.

That request was denied by the court.

• Stephen Dinan contributed to this report.

• Alex Swoyer can be reached at aswoyer@washingtontimes.com.