Proposition 37 requires food manufacturers to have their products labelled as genetically engineered unless these edibles are truly natural or certified organic. This measure was formed for the purpose of protecting the rights of consumers to be aware whether or not the food they buy and consume is genetically engineered.

Genetically engineered products or products with genetically modified ingredients are said to be unhealthy. In fact, the American Academy of Environmental Medicine has been encouraging doctors not to prescribe diets that include intake of GMOs. Consumption of genetically engineered edibles has also been linked to a number of dangerous side effects that can put people's health at risk. To add to this, GMOs are harmful to the environment. The herbicides used for production can cause ill effects to the marine ecosystem, soil organisms, and even to insects and birds. Due to these reasons, the first reaction of the public with regards to Proposition 37 was favourable.

Surprisingly, the state-wide election resulted in Proposition 37's defeat. Despite millions of dollars spent on campaigning for the said measure, more people of California opted for opposition of Proposition 37. There have been a lot of speculations why the California voters reversed their stand. Dirty tricks and lies were just a few reasons that the camp of Proposition 37 pointed out after the loss.

Further studies in this case reveal that more Californians rejected Proposition 37 because they have faith in science. These people believe that the accusations made by the Proposition 37 camp were overly against science and merely meant to frighten the public. Even the experts regarded some of Proposition 37 camp's claims as baseless.