The California Supreme Court has denied an appeal by Bronco Wine Company against a decision by the California Court of Appeal regarding the use of the word "Napa" on its branded wines.

Napa Valley Vintners, a trade association with 270 members, has been battling to prohibit the US wine producer from using the word Napa in brand names, under legislation passed in 2000. The so-called "truth-in-labelling" legislation prohibits companies from using the name Napa in a brand name unless the wine inside is actually Napa wine.

In May, the lower court ruled in favour of Napa Valley Vintners, and the latest ruling moves the case into the final stage of appeals. Bronco is expected to file a petition with the US Supreme Court within the next 90 days.

"Today marks another significant, consecutive victory for winemakers and consumers with respect to truth in labelling," said Linda Reiff, executive director of the Napa Valley Vintners. "We believe that if it says Napa on the label, it better be Napa in the bottle; and the California Supreme Court's decision not to hear this case seems to confirm that."