A ruling from the California Court of Appeals has upheld a state law requiring that wine with "Napa" on its label should be 75%-made from grapes from the Napa region.

Responding to the ruling which was made on Thursday, Kathleen Sullivan, a lawyer representing the Napa Valley Vintners Association, said: "Napa vintners are extremely happy that the brand name that has taken so much hard work and passion to build up over 150 years can now be protected against a knockoff industry and fake Napa wine."

The state law, dating from 2000, had been challenged by Bronco Wine Co. Bronco, the large Central California producer known for its mass-market brand, Two Buck Chuck, had argued that federal regulations which exempt brands established before 1986 from a 75% requirement has pre-eminence over the state law, which had effectively closed that loophole. Bronco said it might yet appeal to the California Supreme Court.