We depend on food labels. If the label has incorrect information, someone with food allergies could have a severe, even fatal, reaction.
Quick thinking on the part of Crystal Johnson, who discovered chocolate covered peanuts in her pecan ice cream, may have saved lives. Peanuts were not listed on the label and should not have been in the ice cream. She has a friend with a peanut allergy and knew this could cause a serious reaction. Ms. Johnson contacted FAAN (Food Allergy and Anaphylaxis Network) and the FDA (Food and Drug Association) as well as Mars, the parent company for Dove who manufactured the ice cream product. She saved the container and the FDA sent someone to her home to test it. The product did indeed contain peanuts and was recalled.
That's how it's done.
By the way, Ms. Johnson did get a letter of apology from Mar's and coupons for free ice cream. Here's the entire article.