The fight over whether MillerCoors can call Blue Moon a “craft beer” is headed for the courts.

In 2012, the Brewers Association, an organization representing US brewers, set new standards for qualifying as a “craft brewer.” First, the size must be “small,” meaning the brewery makes a maximum of 6 million barrels annually. Second, craft brewers are “independent”—less than 25% of the business can be owned or controlled by a maker of alcoholic beverages that is not also a craft brewer. Finally, the brewery must be “traditional,” in that the majority of the alcohol it makes is beer using traditional or innovative ingredients (think: the local honey used by Brooklyn Brewery).

Bottom line: Craft brewers are the little guys making actual beer, not the giant corporations making watered-down beer-like substances.

Then there is Blue Moon, which is owned by MillerCoors. Its signature beer, a Belgian-style white wheat brew with a citrusy flavor, has a stylishly retro label. It wants to be called a craft beer, and whether it should be allowed to, MillerCoors CEO Tom Long argued in an op-ed for CNN in 2012, should “not come from an industry organization, but instead from America’s beer drinkers.”

But a class action suit filed last week says the company is engaging in false and deceptive advertising. It points to MillerCoors’ production of 2.4 billion gallons of beer per year, as well as the fact that the Blue Moon website doesn’t mention MillerCoors, even though the MillerCoors’ website plays up Blue Moon. Bottles and cans of Blue Moon leave out its corporate parentage. The suit also points to the MillerCoors trademarked term, “Artfully Crafted,” used on the website and in marketing materials.

Quartz has reached out to MillerCoors for comment on the suit but has not heard back. This post will be updated with any response.

By marketing its product this way, the suit says, MillerCoors is taking advantage of the premium that beer aficionados are willing to spend for real craft beer, without actually delivering it.

While the lawsuit is filed as a class action, and the complaint states that “the Class is comprised of ‘consumers’ and ‘members of the public,'” the plaintiff —a San Diego, California man named Evan Parent—is currently the only named member of the class. “I imagine as we go forward there may be a few people who come forward,” said his attorney James M. Treglio, who is also an old friend of Parent’s. As for the best possible outcome of the case, Treglio told Quartz, “ideally the marketing of Blue Moon would change and… at least some money would go back to the members of the class for their purchase.”

For its part, the Brewers Association says it doesn’t say what is and isn’t a craft beer—it only defines craft brewers.”Blue Moon would not be a craft brewer,” Paul Gatza, director of the Brewers Association told Quartz, “because it’s owned by MillerCoors.”

Unlike other lawsuits that have alleged that particular labels are misleading, this lawsuit is going after the whole marketing scheme, food and beverage attorney Lindsey A. Zahn tells Quartz. ”This [suit] doesn’t talk too much about the label,” she says, adding that the company is using “Artfully Crafted” in advertisements more than on bottles. “It doesn’t seem like they’re saying this is a craft beer,” she says, comparing it to the recent lawsuit against Tito’s Handmade Vodka which uses the word ”handmade” on the actual bottles. Instead, Zahn says, MillerCoors could be saying that there’s an “art behind creating it.”

It’s not hard to understand why MillerCoors (and Anheuser-Busch In Bev with Shock Top, for that matter) has inserted itself into the craft beer market: Craft beer sales were up 17.6% in 2014, while overall beer sales were up a lousy 0.5%, according to the Brewers Association. MillerCoors, which is not a publicly traded company but a joint venture of SABMiller pls and MolsonCoors (TAP), reported in February that profits were down 12%.