What will happen in these cases? It's hard to say since there are no laws about the "natural" claim, and the Food and Drug Administration has done its best to ignore the issue. An article by Dawn Goulet published on the website of the American Bar Association lays out the recent history: In the early 1990s, the agency started working on a formal definition of the claim but backed off on account of what it called "resource limitations and other agency priorities." That left in place an advisory opinion — as opposed to a binding regulation — saying only that natural foods are those that lack "artificial or synthetic" additives.
The agency punted once again in 2007, in the middle of a furor over whether high-fructose corn syrup was an artificial product or just a natural form of sugar. A representative said, "We're not sure how high of an issue it is for consumers." When Snapple faced a lawsuit over high-fructose corn syrup in 2010, the FDA had another chance but failed to offer any guidance to the courts and said that consumers could read the ingredients off a package and decide for themselves whether they were natural. (That doesn't help with unlabeled GMOs, however.) It also argued that it had more important things to do than rule on what a loosey-goosey term should mean.
The government has a point. Food scientists at the FDA are not equipped to handle such matters of natural philosophy.
When the agency was established at the beginning of the 20th century, its mandate did, in fact, emerge from a crisis of authenticity — what was known back then as the "Era of Adulteration." According to Benjamin Cohen, a professor at Lafayette College who is working on a book about this period, consumers had begun to panic over falsely labeled products: coffee cut with bark and dandelion leaves, sugar mixed with sand, margarine that pretended to be butter.