The same plaintiffs' lawyers that brought down “Big Tobacco” in the 1990s have identified a new villain: “Big Food.”

A slew of lawsuits have been filed over the last four months against 25 food manufacturers, among them ConAgra Foods, PepsiCo, Heinz, General Mills, and Chobani.

Plaintiffs' lawyers say the companies' food-labeling practices mislead consumers. Terms such as “healthy” and “natural” allegedly over-promise health benefits. Alternatively, the lawyers assert, the industry's failure to disclose genetically modified and other ingredients trick consumers into ...