(Fortune) - Spain’s artisanal winemakers are threatening secession if they don’t get new rules on wine labeling.

It was quite literally una muerte anunciada—a death foretold.

At the end of December 2014, top Spanish winemaker Juan Carlos López de Lacalle was so fed up with the wine regulator in his region of DOC Rioja that he said he would discontinue the membership of his 30-year-old winery, Bodegas y Viñedos Artadi, if things didn’t improve. He was tired of being told that he couldn’t specify which vineyard plot produced the grapes on his wines’ labels. Instead, he could only specify a generic region. He’d already begun to rebel, in fact, labeling some of his wines with everything but Rioja (Laguardia, Álava, España).

“You have to answer the demands of the elitist market, which demands above all else personality and character from wine,” says the bookish but intense López de Lacalle, 59. “If we can’t do this in Spain, if we can’t put character and personality and identity in the great wines the country can produce, we’re on the wrong path.”

Though his winery is small—it brings in €3.6 million in annual sales (about $3.9 million)—López de Lacalle’s threat was no small matter. His Viña El Pisón, first produced in 1990, was one of Rioja’s first “single vineyard” wines (using grapes from one vineyard), and the 2004 vintage received a perfect 100-point ranking from wine guru Robert Parker. Artadi was also named 2014 winery of the year by Spanish wine guide Guía Peñín.

And so, when López de Lacalle followed through with his threat in December 2015 and quit the DOC Rioja, he uncorked an argument that bears an eery similarity to Spain’s other great separatist dispute: the one between the secession-minded parliament in Catalonia and the national government in Madrid.

The winery union in Artadi’s zone estimated that 60 wineries might follow López de Lacalle. The DOC Rioja regulatory board put out a pained statement, claiming that López de Lacalle hadn’t fully explained how he wanted his grievances to be addressed. And Spain’s largest daily published a story titled, “The Rioja Wine War.”

Unlike France, most of Spain’s wine regions only allow for broad geographic designations. This is a reflection of the local industry, which is dominated by large wineries that make blends with fruit bought from various grape growers across a region, not by small-production wineries that make wine from one or two local vineyards they often own. Today, 85% of the vineyard land in the DOC Rioja, which spreads across the communities of La Rioja, Navarra, and Basque Country in Northern Spain, is owned by growers, not wineries, says José Luis Benítez, who heads Grupo Rioja, a winery trade association whose members sell 75% of the region’s wine by value.

For blenders who buy grapes from multiple growers, it makes sense to promote their brands with a classification system like Spain’s, which notes the generic provenance of the grapes and ranks wines by how long they’ve been aged. A system that touted specific vineyards would shift power away from the blender.

But in today’s “locavore” consumer market, single vineyard wines have gained cachet because wine buyers want to know the wine’s terroir—that is, the soil makeup and grape variety, as well as the orientation and history of the vineyard the wine came from. And customers are willing to pay more for that, a sensitive issue at a time when Spain’s winemakers are looking to raise prices. A number of small wineries with younger winemakers have opened in Rioja in recent years, and they, like López de Lacalle, have begun to complain that the unique value of their local products is being squandered by regulations designed for large blenders.

“The way the laws are currently framed, they’re not encouraging younger people to invest in the region,” says Tim Atkin, a Master of Wine who covers Rioja as a wine judge and journalist. “They’re preserving the status quo, which is oceans of Rioja sold on supermarket shelves.”

Atkin was one of 150 wine industry professionals who in recent weeks signed a manifesto demanding that Spain’s wine regulatory bodies pay attention to terroir and modify the classification system so specific vineyards can be labeled.