An appeals court in California has ruled that a company can still use the word "Napa" on the labels of certain wine brands, in spite of the fact that the wines contain no grapes from California's most prestigious growing area.

The decision will allow Bronco Wine Company, based in Ceres, California, to continue to sell its Napa Ridge, Rutherford Vintners and Napa Creek wine brands, which are made from grapes grown in Stanislaus county and other areas, as long as it puts the source of the grapes on the label.

The 3rd US District Court of Appeals in Sacramento said it could not interfere with federal regulation of brand names. Napa Valley wine companies have been battling with Bronco, a producer of mass-market wines, for many years. Bronco, which registers sales of around $17m a year from these brands, said that federal regulators had approved the labels.