One of California's most renowned marijuana-growing counties is fighting a federal grand jury subpoena, seeking to protect the names of pot growers who agreed to let the local sheriff inspect their gardens and count their plants.

A federal grand jury in San Francisco has subpoenaed all records for a landmark Mendocino County program that collected $630,000 in permit fees from as many as 500 people licensed as medical marijuana growers in 2010 and 2011.

Mendocino County officials filed court papers Dec. 21 seeking to quash the subpoena as "burdensome and oppressive," saying it violates the county's duty to protect the confidentiality of medical marijuana users and its authority to regulate medicinal cultivation under California state law.

The legal battle, set for a hearing today in U.S. District Court in San Francisco, comes 14 months after federal Drug Enforcement Administration agents raided the farm of Matt Cohen, a grower who won national media attention as a model for Mendocino County's medical marijuana cultivation program.

Cohen, whose Northstone Organics garden in Redwood Valley touted its organic "farm direct" marijuana for delivery to medical patients, has not been charged. But the raid prompted the county to drop its program for issuing permits – and collecting licensing fees – from medical marijuana cultivators.

The sweeping subpoena has stirred fears that federal authorities may use information collected by the county to prosecute pot farmers who paid the county fees and cooperated with inspectors.

The subpoena demands all county documents involving marijuana cultivation permit holders and applicants, plant inspection reports and financial records related to the medical marijuana permitting program.

"We don't know why the subpoenas were issued and really what the (federal) government is looking for," said Kristin Nevedal, executive director of the Emerald Growers Association, an advocacy group representing medical marijuana farmers in the North Coast region. "I think a lot of people are really uncertain about what will happen next."

The local growers association and a medical marijuana advocacy group, Americans for Safe Access, filed court briefs this week supporting Mendocino County's bid to quash the subpoena.

In 2010 and 2011, nearly 100 Mendocino pot farmers who could document they were providing medical marijuana to dispensaries or groups of medical users were given permits to grow up to 99 plants. Under the program, the county sheriff affixed serial numbered zip ties – for which growers paid a $50-per-plant fee – and inspected gardens to enforce plant counts, environmental standards and rules for fencing and security.

Another 400 permits were issued in 2010 and 2011 for growers with 25 or fewer plants who paid $25 per plant for certification.

Donald Heller, a former Sacramento federal prosecutor, said the grand jury subpoena sought by U.S. Attorney Melinda Haag in San Francisco signals that Haag "thinks this is a vehicle to enforce federal law," under which all marijuana cultivation remains illegal. "I think she is going to pick several cases and indict and prosecute," Heller said.

The Mendocino County program was adopted in April 2010 after county supervisors said they wanted rules to help differentiate between medical marijuana providers operating legally under state law and illicit pot growers who trespass on private and public lands.

The grand jury subpoena served on the Sheriff's Department Oct. 23 infuriated members of the Mendocino County Board of Supervisors.

Supervisor John McCowen complained that the federal probe appears to target small, compliant growers rather than criminal networks that grow hundreds of thousands of pot plants in the backwoods of the Northern California coast.

"Why are the feds expending their resources to apparently go after people who participated in this program?" McCowen protested. "Why aren't their resources going after outlaw growers who are trespassing on public and private lands, trashing the environment and endangering the public?"

In their motion to quash the subpoena, Mendocino officials said disclosure to the federal government of "private records of applicants and participating residents" in the county's medical marijuana cultivation program "would have a devastating effect on the program and on the county officials charged with administering it."

It marks the second time in recent months that a local government has gone to court to challenge the federal crackdown on medical marijuana in California.

In October, the city of Oakland sued Haag and U.S. Attorney General Eric Holder, seeking to halt federal efforts to seize the Harborside Health Center, California's largest marijuana dispensary and one of Oakland's top tax-paying businesses.

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