This November, health expert Aaron Carroll will release his latest book: The Bad Food Bible: How and Why to Eat Sinfully. The book debunks common myths about nutrition.
For example, many people once viewed salt as a hypertension-causing monster. Yet, after examining the scientific evidence, Carroll concludes that people with normal blood pressure should be more worried about getting too little sodium than getting too much.
Yesterday’s conventional wisdom can quickly fall out of favor. But what does that mean for the First Amendment? Under the changed circumstances doctrine, one may challenge a statute predicated upon certain facts on grounds that those facts no longer exist.
That doctrine may spell doom for certain labeling laws. For example, a law that required salt producers to disclose “high sodium intake causes hypertension” might have been upheld years ago based on the best scientific evidence at that time. Yet, as the link between sodium intake and bad health outcomes is cast into doubt, so is the constitutionality of any law that requires merchants to affirm that link.
The changing consensus on nutrition also sheds light on why voluntary disclosures usually work better. It’s hard for Congress to enact laws, and even harder for it to repeal them. Thus, a law might remain on the books long after it becomes outdated. And that could leave consumers seeing a lot of labels that don’t make a lot of sense.
The market, however, favors merchants who are able to adapt quickly to consumer preferences. A system of mostly voluntary disclosures is better suited to produce information that changes alongside scientific knowledge and consumer demand.