Whether to label foods as either containing genetically-modified organisms (GMOs) or being GMO-free is getting more complicated. On the one hand, Vermont’s GMO-labeling law, which has thus far survived legal challenge, will require by next July that all foods for sale at retail in the state bear labeling regarding GMO content. On the other hand, many retailers and food producers seeking to capitalize on consumer perceptions that GMO-free foods are healthier, have voluntarily adopted GMO-free labels. No matter if such labeling is voluntary or compelled, the seller faces difficult evidentiary burdens in trying to substantiate GMO label claims. Let’s say it can be proved that GMO ingredients are not contained in a finished food item. How far up the production chain must one go in order to ensure GMOs were not otherwise involved in the process?

Last week, the popular restaurant chain Chipotle was sued in a proposed class action over its GMO-free claims. Chipotle has prominently made serving GMO-free food, and small farming in general, a centerpiece of its marketing. Its anti-GMO marketing stance has engendered substantial public criticism by those who argue the claims pander to unsubstantiated consumer fears of GMOs. As one commenter noted, “Chipotle has . . . pulled off a rare accomplishment: it has managed to unite the ideological left and right among scientists and journalists, a rare occurrence on a controversial science issue.”

Plaintiffs’ lawyers have now taken notice as well. The complaint alleges that Chipotle’s GMO-free claims are false and misleading because its menu has never been free of GMOs. Among other things, the complaint alleges that Chipotle serves meat products that come from animals which feed on GMOs, including soy and corn, that its sour cream and cheese ingredients come from dairy farms that feed animals with GMOs, and that it sells soft drinks that are made with corn-syrup from GMO corn. The complaint does concede that Chipotle posted a disclaimer on its website explaining that some of its soft drinks contain GMO corn syrup and that its meat and dairy products come from animals raised on GMO grains, but says that the disclaimer was ineffective to cure deception occurring elsewhere. Chipotle calls the suit “meritless” and “filled with inaccuracies.”

Others have noted that, even under Vermont’s new stringent laws, GMO’s used as processing aids, or fed to dairy cattle from whom milk is taken, would not require labeling as containing GMOs. The Non-GMO Project, a private standard-setting organization, takes the opposite view, denying GMO-free certification to any such food in which GMOs have touched the production chain through cattle feed and the like.

The only certainty in this uncertain legal environment is that more class actions will likely be filed as plaintiffs start to sense ambiguity and discord on GMO labeling. Until the dust clears, food and beverage makers would be wise to button up their support for GMO claims.