Instead of accusing Monsanto of a flimsy crime like malicious prosecution, or the abuse of legal process, we should go for the jugular and accuse them outright of racketeering and intimidation.
The racketeering comes from the nature of their business. Monsanto developed Roundup back in the 70s, a herbicide which kills all photosynthetic life forms it touches — it seems they just watered down Agent Orange. Then, just before the patent ran out, and after the active ingredient, glyphosate, became industry standard for dealing with pesky plants, they commercialized Roundup-resistant seeds for the most popular crops in the food chain (corn for humans, alfalfa for animals, soy, cotton, et cetera). They lock-in the use of Monsanto brands by subsidiary and independent farmers, and patent the genes of the seeds. This is in case a farmer gets the stupid idea of trying to cross-breed Monsanto seeds with their own. (And even if they do get that stupid idea, terminator seeds make sure nothing will grow from second generation seeds).
The company’s litigious hard-on to destroy independent farmers — however small they are, by offering them a product they cannot refuse — is legendary. And if they can’t sue farmers for “unlicensed” use of their mutant seeds, they can always lobby on Capitol Hill to push through legislation that favors their vile monopoly to fuck around with people’s food. It also helps that they have very powerful ties in Washington, which in turn has very powerful ties to the world they want to mutate.