The Council for Agricultural Science and Technology (CAST) just released a new paper on the impact of process food labeling. The paper was written by a number of top-notch ag economists including Kent Messer, Marco Costanigro, and Harry Kaiser. It's a nice summary of the issues involved in the labeling of food processes (like organic or non-GMO or rbST free) as opposed to labeling food outcomes (like calories).
The summarize five points after reviewing the literature:
They also present a number of challenges presented by these sorts of labels, such as
The authors end with some policy recommendations. Here's the first one: