Not that it undermines your point, but it wasn't soybeans, it was corn. And, as far as the wind blown spreading, corn doesn't pollinate that far from the source. His farm ran next to the Monsanto test farm and, while there was some wind blowing involved, the majority of the seed was gathered by taking seed from the crop next to his farm and by forcefully killing his crops so that he could harvest the resistant corn only. Like I said, it's not as black and white as everyone likes to think it was and there was even accusations that he trespassed on Monsanto property to get the first stock of seeds and they didn't actually blow onto his property at all.

Well, there were accusations during the trial that the seeds weren't even wind-blown and that the farmer trespassed on the property once he saw that the Round-Up wasn't killing the crops. Monsanto argued that they spaced a buffer around their farm to prevent wind-blowing and that they routinely mixed up the perimeter soil to prevent any growth from occurring. Even if we were to be liberal with the probabilities and assume that the seeds could have blown onto his land, the concentration of Round-Up resistant plants on the farmer's land was so unnaturally high that it was easy to prove it was intentional and willful infringement.

>If GM crops are capable of being wind blown how does his activity differ at all from someone trying to naturally select for crops with herbicide resistance?

The only "naturally selected" herbicide resistant crops were made in a lab using fast-neutron bombardment. Not exactly natural, or amenable to traditional methods.

If you tried to select for herbicide resistance in a normal field, all you would get is weeds and a lot of dead crops. It is not impossible to do, simply infeasible.

>Given enough time a superior GMO plant could take over a field all by itself with no intervention

Then you sue the creator and make millions. There is a long precedent with inseticides/herbicide use.

Often if a pesticide blows on the wind into a neighboring field and causes damage, the sprayer is liable. This has already been used to litigate geneflow from one field to another.

>A related problem is that it's difficult/impossible to tell if you're growing a patented seed without expensive tests.

Sampling your soil/crop is actually quite routine in farming. A PCR for a trait can be easily and cheaply performed.

Though, this shouldn't be necessary because farmers usually keep tight control of their genetics. Most commercial farmers (conventional and organic) use hybrid seed. This seed is most fit only for one generation, and as a result they order seed from seed companies to maximize yield. As a result, gene flow is not a huge problem.

Obviously it might be more of a concern for heirloom seed providers, but simply being aware of neighbors and pollination distances can alleviate concerns.

What are the odds that any of the farmers seeds from before the windblown cross fertilization were roundup resistant? Essentially zero, so I have no sympathy for him. If he had not sprayed roundup and some of his seeds got the roundup traits and others did not I would have sympathy for him if he was sued for the mix bag where some seeds had the roundup traits.