I just saw "Food Inc" last night, a 2008 movie about the food industry.
In the movie they detail how Monsanto was targetting farmers who were trying to grow their own seed and suing them. What would happen is that a neighboring farm would be using Monsanto's genetically modified seed and some of the pollen would drift over into the natural farmers soybeans and cross polinate them. Monsanto would then send PIs to find such cross polinated growths and then threaten to sue the farmer for violating their "gene patent" unless the farmer agreed to buy Monsanto seed.
Is Monsanto still doing this? What is the legal basis for this?