Already thwarted by a Fresno judge, a conservative legal organization is pressing its case that federal rules to protect delta smelt are unconstitutional.

In an appeal filed Monday in the 9th U.S. Circuit Court of Appeals in San Francisco on behalf of Valley farms, the Pacific Legal Foundation argues that the government cannot enact the regulations because smelt are not involved in interstate commerce.

U.S. District Judge Oliver W. Wanger rejected the complaint last year, ruling in favor of the federal government. The lawsuit was filed on behalf of three San Joaquin Valley farms that say the smelt rules have led to water pumping cutbacks that have hurt their operations.

The government argued that the "relevant regulated activity" did not concern the smelt, but rather the operation of the state and federal water systems, which "substantially affect interstate commerce."