Of course companies can choose to label their products if they like. There is nothing prohibiting voluntary labeling, and many companies do it. In fact, there’s an easy way to know if a product does not have GMOs: look for the "Organic" label. But this issue is more complex because labeling could be very confusing, as I’ve recently discussed on the Truth About Trade & Technology blog. An excerpt from my entry, which addresses your question, is included below:
“Experts at the U.S. Food and Drug Administration say that food with GM ingredients is safe and perfectly healthy, so there’s no need to label. The American Medical Association and a long list of reputable groups agree. They’re right: Food with GM ingredients is the same as food without GM ingredients. It tastes the same and, in many cases, scientists can’t tell the difference between them.
"Labels won’t help consumers make better decisions, but they’ll increase the cost of food because the labels aren’t free. They represent a significant new regulation on farmers and food companies. The added expense of compliance will be passed along to consumers. We’ll all pay more for what we eat at grocery stores and restaurants.
"At a time when the U.S. economy is at best sputtering along in New Jersey and elsewhere, we shouldn’t pass pointless laws that make it harder for families to feed themselves.
"It would be bad enough if the negative impacts of excessive labeling with information of no use to human health or safety were to stop there. Yet they’ll extract an even higher toll as they call into question the very purpose of GM technology. Consumers may begin to wonder why this food needs labels in the first place—and they may start to avoid it.
"That would be a tragedy. Biotechnology lets us grow more food on less land. That’s why I grow GM crops on my farm, not far from where Assemblywoman DeCroce cast her wrongheaded vote in favor of an unnecessary labeling law.
"As we struggle to feed our families in tough times—and try to find ways to feed a growing global population—we need to appreciate food grown with the benefit of biotechnology as part of the solution rather than part of the problem.”