On the scientific front, experts appear divided. Opponents of the measure argue that the long-term health risks could be significant. Proponents argue that there is no evidence yet of any risks and that the higher crop yields offered by genetically modified organisms (or GMO's) are critical to feeding a growing population.
But for organic farmers like Phil McGrath, GMO crops pose a very specific problem -- something called pollen drift, in which nearby GMOs transfer genetic material to traditional or organic crops through cross pollination.
"If they're growing a GMO crop and the wind comes up, the pollen comes into my organic fields. I can lose my certification. It would devastate my operation out here," McGrath told correspondent Jennifer London.
McGrath spent some time with our friends over at KCET's Departures explaining the benefits of organic foods to the health of the people who consume them and to the land that sustains them. However you feel about Prop 37, it's helpful insight into the thinking in that camp, and might help to explain why so many organic farms and food companies have donated substantial sums of money to see it pass.