Lawyers for the Drakes Bay Oyster Co. and Interior Secretary Ken Salazar will square off Friday before a federal judge in Oakland in the first round of a legal battle to continue the commercial oyster operation in the Point Reyes National Seashore.

At stake is Salazar's decision in November not to renew a 40-year lease that gave oyster farm operator Kevin Lunny the right to commercial operations in 2,500-acre Drakes Estero, a five-fingered estuary that features extensive eelgrass beds and a harbor seal colony.

The decision, hailed by wilderness advocates, gave Lunny's company 90 days to shut down a business that plants and harvests 8 million oysters — worth about $1.5 million a year — from the near-pristine estero. The deadline was subsequently extended to March 15.

Four days after Salazar's Nov. 29 decision, a Washington, D.C.-based nonprofit filed a federal lawsuit alleging it violated federal rules and was based on faulty science.

"The government has doubled down on bad science, refusing to listen to anyone who tells them anything to the contrary," said Amber Abbasi, an attorney for the group Cause of Action, who will argue Lunny's case on Friday before U.S. District Judge Yvonne Gonzalez Rogers.

Abbasi said she will ask for a temporary order postponing the oyster farm closure until the legal case is resolved.

The closure, Lunny's lawsuit said, would cause "immediate irreparable pecuniary and nonmonetary harm" to Lunny, his company and its 31 fulltime employees.

Cause of Action is a government watchdog group that provides legal services at no cost to clients.

Abbasi said the case zeroes in on legislation authored by California Sen. Dianne Feinstein in 2009 giving Salazar sole discretion to renew the oyster company's permit for 10 years.

The permit granted by the National Park Service "provided for renewal" and Feinstein's measure "fast-tracked" the process, Abbasi said in a telephone interview.

"If the government is not going to issue a permit, you have to be treated fairly," she said.

The lawsuit alleges that the Interior Department failed to comply with rules for an environmental study that would enable Salazar to make "an informed, reasoned decision" on the permit.

Stephen Macfarlane, a Department of Justice attorney, declined to comment on the lawsuit.

In a response to the lawsuit filed Jan. 9, the government asserted that Salazar's action was not subject to environmental rules and that the "allegations of scientific misconduct are baseless."

The response noted that Salazar's own memo said the decision was "based on the incompatibility of commercial activities in wilderness and not on ... data that was asserted to be flawed."

Further, it said the financial harm cited by Lunny was "a foreseeable consequence" of buying the oyster farm from a previous owner in 2004.

In closing, the government asserted that establishing "full wilderness status" to the estero "fulfills a principal goal for the seashore that Congress defined over 36 years ago, and is therefore manifestly in the public interest."

The six-year battle over the oyster farm's status sharply divided the West Marin community and attracted global interest.