I'm also in favor of mandatory labeling of genetically modified crops when the whole crop is what is eaten by humans. I think soybeans are the only example of that, although maybe papaya is an exception. The "Artic Apple" and farmed salmon are somewhere in the regulatory process.
Right now, most GM crops are fed to animals (corn and soy and alfalfa), or used to produce corn oil, high fructose corn syrup or beet sugar.
Almost every processed food you can buy has some corn oil, high fructose corn syrup or beet sugar.
Therefor, almost ALL processed food right now would have to have a "GMO ingredients" label.
Persoanlly, I would not label those! I would save those labels for the "GMO foods" now in the pipeline, like sweet corn for humans, non-browning apples, farmed salmon, and whatever else.
Almost everyone knows that almost all processed foods contain corn oil, high fructose corn syrup or beet sugar.
I think most people with concerns about GMOs used to produce food realize that beets and corn are mostly GMNO today.
Those three products, though they may be nutritionally empty of demonic, are practically chemically pure as normally produced. Certainly don't contain Bt toxin, or enzymes for RoundUp resistance, or residual RoundUp. The process of extracting them makes the source (GM or normal crops) almost irrelevant.
I wish we would save our indignation and votes for labeling "real" GMO foods that are mostly not commercial yet. When someone says that CURRENT GMO ingredients are “substantially equivalent” , they could substantiate that down to the molecule with gas chromatography and mass spectrometers. But that's bait-and-switch.
Beet sugar and high-fructose corn syrup could almost be sold as chemical reagents. As ingredients their medical danger is that they are empty calories, not the risk that the GM crop tey came from produced "different" beet sugar molecules or "different" fructose.
The medical danger (if any) will come from the genetically engineered foods where we eat the whole apple, or the whole salmon or whole papaya. THOSE are what I really, really wish would have mandated labeling.
Of course, no one would buy them (at first) unless they were half the price. I think "the plan" was for those foods to be marketed at full price even though they will be cheaper to produce or distribute. Call me cynical.
I personally think there is a lack of scientific evidence that food animals are suffering much if any bad effects from a diet that is 80% GMO , based on the few GMO crops that have been approved for animal feed (corn, soy and alfalfa are all I recall).
On the other hand, I would also say that it's almost impossible to "prove" that something has "no" effects - and I understand people wanting to see long-term studies done on humans. We only have that now for processed foods, but lacking the control group that does not eat pro3ecessed foods. If indeed organic-food-eaters have lots less obesity and diabetes, that would be a great data point to argue with! But we would still have to separate the effect of a HEALTHY diet vs. a processed food trash diet, to winnow out the effect of GMO ingredients.
Most of all, everyone is entitled to their own opinions and degree of cynicism - and they can choose to be cynical about agribusiness, governments, the media, and food safety activists. I don't even think most of us choose that, it's as if were born distrusting certain groups more than others, but that's the human condition.
I haven't heard any argument that seems strong yet for DIShonesty in labeling! And there sure are some strong feelings of "I WANT TO KNOW !!" in a lot of people, including many people who think that the GMOs we've seen so far seem "safe enough for them".
Just one thing: as several states pass mandatory GMO labeling laws, we are starting to acquire a mish-mash of conflicting and overlapping regulations. Soon that WILL make compliance expensive. We need one centralized set of GMO labeling laws, like at the national level.
I vote for making a big distinction between "this box has beet sugar that came from a GM beet" and "this GM salmon was farmed in sludge so dirty that it needed special genes to self-medicate just so it could survive long enough to harvest". Or "this fresh-LOOKING apple would have been bruising and brown and flaccid if it didn't have special enzymes keeping it attractive".
What I really wish they would use GE tools for is to create crops that can withstand marginal conditions like drought and heat and low-fertility. Things that matter to starving people in the Third World. &Use GE to cure hunger, not to increase "attractiveness" and "marketability".
The "First Generation" of genetic engineering tools were somewhat haphazard and slow to use, and they always dragged in some "alien" or transgenic genes (that was based on Agrobacterium's ability to infect the genome of plants using its plasmid). That dragged in all the DNA from the Agrobacterium's plasmid, plus the desired new genes, plus promoter 5regions and terminator regions and regulator sequences ... and inserted that entire mess into random locations on a random chromosome in the target plant. (That's why they need their own promoters and regulators, etc).
The "Second Generation" of GE tools include TALENS and CRISPR, but CRISPR is a big improvement over TALENS. Faster and cheaper, but most of all, much more precise and able to "edit" instead of "add". Plant geneticists can now modify very small regions of DNA in the plants OWN genes, chnaging as little as just one nucleotide, or editing one gene in a crop plant to match that same gene as expressed in a wild variety of the same species. They don't have to use transgenic DNA pasted in willy-nilly anymore.
That's good for under-funded labs and small country's research labs. They can work cheaper and faster to produce plants with less First World profitability, and more Third World relevance.
Before, it took a company as big and rich as Monsanto to fund a multi-year development of transgenic crops plus the multi-year certification process. They only did that for the Big Bucks. CRISPR lets small labs experiment with things that could save lives, not just save money.
There will probably be discussion over whether CRISPR-modified plants need as much field testing before release as the transgenic Agrobacterium GMOs did. My prediction is that Third World countries will start saving lives faster than the USA certifies them.
soy is another product similar to corn that is hidden in just about everything. Like corn I am sure it has a dozen fancy names and even after reading a label you still don't know what's in it! I have had to do a lot of research. 
