I don't know what case you are referring to. The only case I found involved Percy Schmeiser of Saskatchewan, Canada (see
http://articles.mercola.com/sites/articles/archive/2011/12/25/percy-schmeiser-farmer-who-beat-monsanto.aspx ). His fields were contaminated by pollen from outside his fields by Monsanto GM crops. Monsanto then sued him because he didn't license the GM crops from Monsanto.
He eventually won the lawsuit, although the courts there did say farmers don't have a right to use patent protected genes in their crops even when they are unwanted but inadvertently added from outside.
There is a real problem with GM crops is that the genes can spread to crops that are not licensed to have them. Patent law is not well-developed in this area because the patent can be unintentionally violated by farmers who would never want the genes in their crops in the first place. For example, it's not clear whether or not a grain elevator operator who buys grain with GM genes can't turn around and sell it as seeds to other farmers, even though the farmers themselves cannot.
Most farmers have to deal with Monsanto even when they don't use GM crops. Few farmers actually grown their own seeds, and Monsanto has a big market share in the market for non-GM seeds.
