If, however, the farmer were to sell those replantable seeds, the person that bought them could not be penalized under this decision. More relevantly, the cases where Mosanto allegedly went after people who grew patented crops from seeds that blew into their fields would now have no legal leg to stand on.
The "Monsanto sues a farmer for growing crops that happened to have been contaminated by GM pollen" thing never had any leg to stand on. When a
group of farmers sued Monsanto out of fear of
exactly the situation described, it was thrown out because there was no incident where Monsanto had ever actually sued anyone for growing accidentally contaminated crops.
In response to plaintiffs’ [farmers] letter, defendants [Monsanto] reiterated that it is not their policy to exercise their patent rights against farmers whose fields inadvertently contain trace amounts of patented seeds or traits. In particular, the reply letter referenced plaintiffs’ claim that they do not have any intention of using any transgenic seed and noted that, “[t]aking [that] representation as true, any fear of suit or other action is unreasonable, and any decision not to grow certain crops unjustified.” (FAC, Ex. 4, Letter from Seth P. Waxman, WilmerHale, to Ravicher (Apr. 28, 2011).)
There was one infamous case in 1999 where Monsanto sued Percy Schmeiser, a Canadian canola farmer, for growing "Roundup Ready" crops without having paid the licensing fee. Schmeiser had never actually purchased any of Monsanto's seeds, and he claimed that the crops had been contaminated by GM pollen. In that case, however, Schmeiser had deliberately selected seeds from some of his own crops to replant when he noticed that they demonstrated a resistance to Roundup (due to unintentional cross-pollination from a neighboring field that did use Roundup Ready canola; Schmeiser knew about the GM crops in the neighboring field and performed an experiment to see if any of his nearby crops showed a similar resistance). Monsanto sued because Schmeiser purposefully used seeds that he suspected contained patented GM traits without paying Monsanto's licensing fees; in other words, he intended to infringe on their patent.
In any case, the ultimate decision in that case was that Schmeiser
had deliberately infringed on Monsanto's patent, but because doing so didn't benefit him (he had no intention to use Roundup on his crops, which sort of makes you wonder what the point of it all was), he didn't owe Monsanto anything.