I have nothing against GMOs. What I do have a problem with is patents on genetics.
I think that's what a lot of the more educated anti-GMO activists have a problem with as well. Nobody should be able to patent a life form or a DNA sequence.
The crazy thing is, unlike the DNA patent for testing for breast cancer which has finally gotten SCOTUS' attention, there is no indication that a GMO will ever not meet the bar of a utility patent given the amount of purposeful engineering involved. The issue is more about whether the government should allow the entire world's food chain to be completely at the whims of a single, monopolistic patent holder.
There are a variety of plant-variety-protection acts that were originally penned to protect fruit tree breeders from having their competitors just grow seedlings from their painstakingly cultivated strains that often took decades of greenhouse breeding. Such protections have exemptions built in allowing farmers to re-plant seeds, as well as research exceptions and other public-safety provisions (i.e. if the government can step in if licensing terms would cause a famine, for example). The fine line that Monsanto treads is that, to anti GMO activists, they claim that a GMO is really just a souped-up type of selective plant breeding that we have been doing for centuries, so it shouldn't require any special environmental or public health regulations. But when it comes to licensing disputes, they insist that GMOs are so sophisticated and totally unlike a traditional "plant variety" that they deserve a utility patent and not ordinary plant variety protection. They can't have their cake and eat it too. Someone needs to found the AMD of GMOs and take away their cake. And then maybe they'll stop using lawyers to force 20-year-old genetic technology down farmer's throats and actually innovate for a change.