California Proposition 37, the Right to Know Genetically Engineered Food Act, was defeated in November 2012 with 48.6 percent of the vote. It came within roughly 1.4 percentage points of passing, after starting the campaign season with polls showing support above 60 percent. Opposition spending, largely from agricultural chemical and packaged food companies, was several times the yes campaign’s budget.
The measure would have required labeling on raw and processed foods containing genetically engineered ingredients and barred those products from being marketed as natural. It would have made California the first state to mandate such labeling.
What happened afterward is the part worth knowing, because the story did not end at the ballot box.
the labeling exists now, and it is federal
Vermont passed a GMO labeling law that took effect in 2016. Congress responded within weeks by passing the National Bioengineered Food Disclosure Law, signed in July 2016, which preempted state laws and directed the USDA to write a national standard. The USDA published that standard in December 2018, and the mandatory compliance date was January 1, 2022.
So since the start of 2022, packaged food sold in the United States has been required to disclose bioengineered ingredients. The disclosure can be text, a symbol, a phone number or a QR code that consumers scan.
The federal rule is narrower than Prop 37 was in several ways that matter. It uses the term bioengineered rather than genetically engineered or GMO. It applies only to foods containing detectable modified genetic material, which excludes highly refined ingredients like soybean oil and beet sugar derived from bioengineered crops, because the processing destroys the detectable DNA. That is a substantial carve-out: refined oils and sugars are where most bioengineered crop tonnage ends up. It also does not cover meat, poultry or eggs from animals fed bioengineered feed, and it permits QR codes, which functionally hides the information from anyone without a smartphone in the aisle.
the consumer right argument versus the safety argument
The case for labeling that holds up is about disclosure, not danger. Consumers can reasonably want to know how their food was produced, the same way they can want to know it is kosher, organic or from a particular country. That is a preference argument and it does not require the product to be harmful.
The case that labels warn of a health risk is where the evidence runs out. The National Academies of Sciences, Engineering, and Medicine published a 900-page review in 2016 covering two decades of research and found no substantiated evidence of differences in risk to human health between currently commercialized genetically engineered crops and their conventional counterparts. The American Medical Association, the World Health Organization and the European Commission’s own research reviews have reached broadly similar conclusions on the crops that have been approved.
Both those things can be true at once: you can support knowing what is in your food while accepting that the science on approved GE crops has not found a health problem. The 2012 campaign frequently blurred that line, and blurring it is what gave opponents an opening.
the 61 countries claim
A figure that circulated constantly in 2012, and still does, is that 61 countries already require GMO labeling. The number was roughly accurate for countries with some form of mandatory labeling regime on the books, but it obscured enormous variation in what those regimes required and how they were enforced.
The European Union threshold is 0.9 percent of an ingredient, above which labeling is required, with exemptions for animals fed GE feed. Japan’s threshold was 5 percent for listed ingredients. Some countries on that list had laws with little practical enforcement. Counting regimes as equivalent when their thresholds differ by a factor of five is the kind of shortcut that makes a true statistic misleading.
what the label does not tell you
If your interest in avoiding bioengineered ingredients is really about pesticide exposure or farming practices, the BE disclosure is a poor proxy for either. Glyphosate-tolerant crops changed which herbicide gets applied rather than eliminating application, and some bioengineered traits, such as Bt insect resistance, reduced insecticide applications. The relationship between the label and the chemical exposure is not one-directional.
The USDA Organic seal is a more informative label for that purpose, since it prohibits both genetic engineering and most synthetic pesticides, and it comes with third-party certification and inspection. It also costs more and its own nutritional claims are weaker than marketing suggests. The Non-GMO Project butterfly is a private certification with its own standards, which are stricter than the federal rule in some respects and are not government-verified.
reading a package in 2026
| Label | Who verifies | What it means |
|---|---|---|
| Bioengineered / BE symbol | USDA, mandatory since 2022 | Contains detectable modified genetic material |
| USDA Organic | Accredited certifiers, inspected | No GE, most synthetic pesticides prohibited |
| Non-GMO Project Verified | Private third party | Tested supply chain, stricter than federal rule |
| Natural | Nobody meaningfully | Almost nothing in a legal sense |
That bottom row is the one Prop 37 also tried to address by prohibiting natural claims on engineered foods. It failed, the FDA has still never established a binding definition of natural for food labeling, and the word remains one of the least regulated terms in the aisle.
Prop 37 was a policy fight about disclosure that got argued as a fight about safety, which is a decent explanation of how a measure polling above 60 percent ended at 48.6. The disclosure it wanted now exists in weaker form. If you want to know how your food was produced, the organic and Non-GMO seals carry far more information than the federal symbol does.