A federal appeals court ruled Tuesday that a label on ConAgra Brands Inc. frozen chicken was not enough to prove its featured product claims had been authorized by the agency governing the label approval process, which is a dispute at the center of a proposed consumer class action.

In a 17-page opinion, the U.S. Court of Appeals for the Ninth Circuit reversed in part an order dismissing a false advertising case over ConAgra's "no-preservative" chicken products, which contain three synthetic ingredients.