Put down your carnitas burrito and give a side-eye to your soda. Chipotle has been sneaking GMOs into its “non-GMO” menu offerings — or at least, that’s what a recent class action lawsuit claims.

Back in late April, Chipotle announced that it was “G-M-Over It,” rolling out a marketing campaign that declared the restaurant chain would only use “non-GMO ingredients.”

“When it comes to our food, genetically modified ingredients don’t make the cut,” read advertisements for the fast-casual chain. (You’ll probably recall that the media reacted quite critically and wasted no time in lambasting the company.)

Apparently, consumers in California were equally dubious. In her class action lawsuit filed last week in federal court in San Francisco, lead plaintiff Colleen Gallagher of Piedmont, Calif., alleges that Chipotle deceived customers into paying more for its food and violated the Federal Food, Drug, and Cosmetic Act with its false and misleading food labeling.

The lawsuit, filed on behalf of California consumers who bought food from Chipotle after April 27, 2015, says that the advertising campaign is deceptive and misleading because many menu items do contain GMOs and that the plaintiff was injured “by purchasing (or overpaying for) Chipotle’s Food Products” (see page 18) and that “[p]laintiff would not have purchased Chipotle’s Food Products (or paid as much for it) had she known the truth” (page 19).

It is a bit strange that Chipotle, the restaurant chain that has done the most work to align itself with the people who worry about eating GMOs, has become the target of ire for people who worry about GMOs. But on the other hand, it makes perfect sense: You can’t expect everyone who sees GMOs as a hazard to agree on how to define acceptable practice. Some GMO-objectors are only concerned about the herbicides used with herbicide-tolerant plants, others worry about just some GM crops, others would prefer to avoid everything that was engineered in a lab but are happy to eat animals that ate GM feed, and finally, there are those who won’t touch GM-fed meat and dairy. Chipotle’s stance makes perfect sense to most of the anti-GMO crowd, but to the most exacting critics, the company’s position looks deceptive.

By contrast, McDonald’s is probably not going to announce that it’s going to be “G-M-Over It” anytime soon — and as a result, it doesn’t receive the same kind of scrutiny.

The plaintiffs claim that “Chipotle serves meat products that come from animals which feed on GMOs, including corn and soy.”Furthermore, the restaurant’s soft drinks are made from corn syrup, and its sour cream and cheese come from dairy farms that give animals GMO feed. (According to the USDA National Agricultural Statistics Service, more than 90 percent of corn and soybeans grown in the U.S. came from GMO strains in 2014.)

Laurence D. King, an attorney with Kaplan, Fox & Kilsheimer LLP, the law office representing the plaintiffs, said because consumers today are “very concerned about what they eat,” Chipotle should have, well, known better. The class action complaint claims that, if not for this lawsuit, Chipotle will go about retaining the proceeds of “its ill-gotten gains” (see page 16).

“Chipotle’s advertising in its stores should have accurately informed customers about the source and quality of its ingredients and should not mislead consumers that they are serving food without GMOs when in fact they are,” King wrote in a statement.

Chipotle spokesman Chris Arnold said over email that the allegations are “meritless” and that the chain plans to fight it, adding “a lawsuit is nothing more than a series of allegations and is proof of absolutely nothing.” He was quick to add a dig at the lawsuit’s sloppy homework: “We have not done any television advertising concerning GMOs at all, and the lawsuit blames us for graphics that we did not create or authorize.”

Arnold said that Chipotle knew the corn given as feed was GMO, and that the chain has always disclosed that. “Virtually all corn and soybeans grown in this country (upwards of 90 percent of each) are GM varieties, and it would be nearly impossible to avoid serving meat from animals that were not given GMO feed,” he wrote. “Feeding an animal GMO feed does not genetically modify the animal, any more than you or I would be genetically modified if we ate GMO foods.”

Chipotle has about 100 key suppliers, Arnold said, and each of those has a network of farms from which it sources. For instance, Niman Ranch, which bills itself as a “leader in sustainable agriculture and humane livestock practices,” is one of Chipotle’s more well-known suppliers and has a network of “500 or 600 farmers” who provide their pork. Niman’s other customers include Whole Foods, Sprouts, Panera, Shake Shack, and Au Bon Pain. Niman Ranch did not respond to media requests from Grist.

Indeed, Chipotle’s ingredient statement very clearly states, “While we are striving to eliminate GMOs from our supply chain, there is currently not a viable supply of responsibly raised meats and dairy from animals raised without GMO feed.”

When it comes to monitoring the farms from which Chipotle sources, Arnold added that the chain uses “very few ingredients” where there are genetically modified varieties “so the universe of things we need to monitor is relatively small, and would primarily be corn and soy.” The soy it uses for its tofu, for example, is certified organic and non-GMO “by virtue of that,” in Arnold’s words. Other ingredients go through a combination of seed specification, audits, documentation, and testing.

Arnold also pointed out that most GMO labels exempt animals fed on GM grain.

“The Vermont rules exempt meat and dairy from animals that were fed GMO feed, so, under their rules, the meat and dairy we serve in our restaurants would not be labeled as GMO if sold at retail (the labeling requirements only apply to retail),” he wrote. (Vermont is the only state to pass a GMO labeling requirement, which goes into effect in 2016.) “Similarly, the Safe and Accurate Food Labeling Act of 2015 (HR 1599), which recently passed the House of Representatives, proposes voluntary non-GMO labeling guidelines that would also allow food to be labeled non-GMO if it is produced with genetically engineered processing aids, or animals given GMO feed. We are absolutely on solid footing in calling our food non-GMO, and have no reservations about that.”

We also reached out to a California attorney (who has no associations with either the law firm bringing the suit or the plaintiffs) to ask whether it holds any water. Thomas Girardi, with the law office of Girardi and Keese, told us that it’s hard to win a class action suit that concerns personal injury in a food case. “Some people got massively sick, some people were emotionally upset, so the damages are all very different,” he explained, adding that it would have been better to have filed it as a mass tort action for anyone who was “truly injured” because the individual damages would be separate.

This isn’t the first time Chipotle has faced a class action lawsuit. When I asked Arnold how many other suits of this nature have been filed against the chain, he said over email that he’d have to get back to us, adding that “our track record in contesting lawsuits in general is quite good.”

Maybe this lawsuit isn’t going anywhere, but if it does travel onward, what a trip it will be.