So the question you ask in parenthesis is different from the question you ask int he first paragraph. If you prove the plant existed widespread in the wild before the patent holder tried to apply for the patent, then yes, the plant is not patentable. Furthermore, if the variety is not reproduced asexually, then it is not patentable. This is basically plant prior art. You cant patent air conditioners because they already exist.
However, if you do what you mentioned in the first paragraph and go and propagated a ton of plants and make them widespread after the fact, then no you haven't invalidated the patent. You just infringed on it even more and probably have to pay a bigger fine. In general, you don't get to escape the legal consequences of an action by doing the action even more times. That just makes the consequences worse.
Oh, I get the bad guy is hosed, but what about the wildfire propagation? Sued unto the n'th generation? How long does the gene continue to be bound by patent law, once its propagating freely?
Suppose I drop a ton of these seeds all over the place. Some land in your backyard. Some of those take root.
The next year, you notice some volunteer grapes growing on your fence, taste one, and decide it's pretty good. If you give some to your friend so they can plant the seeds, are you culpable? If you sell some, are you culpable?
If its propagated by seeds its not patentable - so I don't think it's possible for that sort of scenario to rise. If you asexually propagated a plant and let a neighbor take a cutting, then I'm not sure. I'm not a lawyer, but that situation sounds similar to the what happens if you unknowingly buy stolen art and try to auction it type question. It would probably be a very interesting legal battle at the least - and the original propagator would probably be liable, but that's definitely an interesting scenario. I doubt the end result is going to be that the patent owner just loses protection.
I believe Monsanto sued a farmer accidentally pollenated with their patented genome, wind borne. I believe Monsanto won: he had to pay in some form or another. Not surprisingly, other organic farmers have sued when their non-GM crops were tainted by windborne patent encumbered pollen, and I believe they sometimes lose and sometimes win. It depends.
No, Monsanto sued a farmer who concentrated glyphosate resistant traces in his soybeans by spraying his field with that herbicide. Had he not done that, Monsanto would have done nothing (and likely could have done nothing). The courts properly recognized the farmers conduct as willful patent infringement.
indeed as you said: "The Supreme Court found that Schmeiser’s actions constituted infringement. Monsanto’s evidence at trial, estimating that 95-98% of Schmeiser’s 1000+ acres contained canola plants with its patented gene, convinced the Supreme Court that the infringing gene’s presence was too pervasive to be caused entirely by accidental delivery."
Those aren't plant patents, those are DNA patents, completely different from the plant patents being discussed here. The patent there is on the dna sequence, not the plant. If you took that dma sequence, cloned it into yeast, amd started fermenting the enzymes the sequences produced, you'd also be 8 fringing that patent - jt has nothing to do with the pollen or the plant, the plant just happens to be what the patented item is in.
However, if you do what you mentioned in the first paragraph and go and propagated a ton of plants and make them widespread after the fact, then no you haven't invalidated the patent. You just infringed on it even more and probably have to pay a bigger fine. In general, you don't get to escape the legal consequences of an action by doing the action even more times. That just makes the consequences worse.