CHEYENNE, Wyo.—The Wyoming Supreme Court is scheduled to hear oral arguments Nov. 20 over whether the public has the right to obtain lists of chemicals used in hydraulic fracturing or if those ingredients are corporate trade secrets that may be shielded.

The Wyoming Oil and Gas Conservation Commission adopted its first-in-the-nation fracking chemical disclosure rule three years ago. The rule requires companies that frack in Wyoming to provide the commission with lists of the chemical ingredients in the fracking fluids they use.

The idea is that if groundwater pollution ever occurs near an oil or gas well, the commission—which oversees oil and gas development in Wyoming—would be better able to determine if fracking played a role.

Environmentalists and others want access to the information, too. They say landowners need to know about the chemicals so they can have their groundwater tested for them.

Fracking boosts production of oil and gas wells by pumping pressurized water, sand and chemicals into the wells to create underground fractures. Environmentalists fret that fracking can pollute groundwater, but industry officials say environmentalists have vastly overstated the risk.

In 2011, the Powder River Basin Resource Council, Wyoming Outdoor Council, Earthworks and Center for Effective Government filed an open records request to obtain fracking chemical lists submitted to the Wyoming Oil and Gas Conservation Commission.

The commission didn’t supply the lists, prompting the groups to sue.

Natrona County District Judge Catherine Wilking sided with the commission in March. She ruled that the state oil and gas supervisor, who directs the commission staff, didn’t overstep his authority in determining that the lists were trade secrets that needed to be kept out of the public eye.

The commission carried ahead with that argument in a brief filed with the Wyoming Supreme Court. Halliburton Energy Services is one company that makes and sells products in a competitive market for fracking fluids and has joined the state’s side in the lawsuit.

The chemicals are an “integral part of the formula” for fracking fluids and “are clearly the product of substantial intellectual and monetary commitment by the operators,” the commission brief states.

Attorneys for the groups say they’re not interested in obtaining the formulas, just lists of individual chemicals, which they argue aren’t protected trade secrets under Wyoming’s public records act.

In the year after the disclosure rule took effect, the commission granted 50 industry requests to exempt chemical lists from public release. Doing so withheld some or all identifying information for about 190 chemicals, according to the groups’ brief.

Former state Oil and Gas Supervisor Tom Doll’s justifications for withholding the lists were often “boilerplate, conclusory and often focused on the confidentiality of formulas, not individual ingredients,” they argue.

Judge Wilking, they say, erred in deferring to the supervisor to interpret the open records act to withhold the chemical lists as trade secrets.