The central question before the court is how to decide how much air pollution from Northshore Mining is allowed.
The way a federal judge answered that 30 years ago was by saying Reserve Mining could not put any more asbestos-like fibers into the air around the nearby town of Silver Bay than there were in a control city, St. Paul.
He issued an injunction to that effect, and he said if anyone wanted to clarify or change that ruling, they should ask that federal court for help.
Three decades later, the injunction is still in effect, but Northshore argues it's met the requirement and so the control city standard should be dropped.
In the meantime, the state incorporated that standard into the permit that governs Northshore's operation.
So attorneys from Minnesota, joined by colleagues from Wisconsin and several environmental groups, argued that Judge Paul Magnuson should stand aside and let the state be in charge.
Kevin Reuther is an attorney for the Minnesota Center for Environmental Advocacy.
"There are very good reasons for the judge not to take up this matter at this point, and to send it back to the state agency and the state courts," said Reuther.
He says Northshore is ignoring established state procedures.
Northshore's argument is the company met the standard years ago, when it installed pollution control equipment that brought fiber levels down below the levels in St. Paul. The problem is, more recently St. Paul's levels have dipped below Silver Bay's.
That's unfair, according to Dana Byrne, vice-president for public affairs at Cleveland-Cliffs, which owns the Northshore mine.
"Our position is we've met that standard, that standard was established. Now, boiling it down, they've moved the bar on us," said Byrne. "They're saying they can do that, and we're saying no, that standard was set and we've continued to meet it. So that's really, in layman's terms, what's going on here."
The state argues it's normal to gradually lower the bar in efforts to control pollution. Ann Foss is mining section chief at the Minnesota Pollution Control Agency.
"Technology has advanced over time, so that they should be able to live with lower levels, they've demonstrated that they can comply with the current levels in St. Paul, and we know that there are further reductions they could make at the plant," Foss said.
In fact, Foss says the company has been in compliance with even the lower St. Paul levels in the last several months.
Earlier this month, the MPCA notified Northshore the agency wants to create a defined limit for asbestos-like fibers. Foss says this would be a refinement of the control city standard, although it would not replace it.
"A more set number so they that know exactly what the number is, they don't have to worry about every time we get a St. Paul number that it will change the standard," Foss said. "And we talk about the fact that then we would also have the permit clear that we can reopen permit to put in a health-based standard."
That health-based standard is what everyone says they're waiting for. The control city approach was chosen originally because no one has established a health-based standard.
Now, federal and state agencies and the University of Minnesota are working to define that standard. Dana Byrne says Northshore is looking forward to the results of several studies just getting underway.
"We're going to work very closely with the University of Minnesota in their study, so hopefully the data will be collected to demonstrate once and for all whether the type of ore we mine, or the taconite on the Range, causes any increased level of health concerns," said Byrne.
The company is also asking a state judge to remove the control city standard. That case is awaiting oral arguments. It could be months before either is decided, and years before a health-based standard is worked out.