Two biological phenomena give rise to a certain number of risks linked to HTV use: the diffusion of the HT trait: via, on the one hand, the HTV’s direct descendents (whether within or beyond the agricultural field), and, on the other, via hybrid carriers of the HT trait resulting from crosses with the HTV. This first mechanism will depend on the plant species involved; the appearance and spread of new, spontaneous mutants that have acquired resistance under the selection pressure exerted by the herbicide. This second mechanism is a function of the herbicide’s mode of action and conditions of use.