In the past years, research on military applications of neuroscience has grown in sophistication. We may expect that future neuroweapons will be advertised as resting on the most objective form of human cognition, leading to greater accuracy in targeting and better compliance with the law than traditional weapons. Are states using weapon systems that draw on neuroscience capable of applying IHL to that use? Only at the price of a decision review system so fundamental as to eradicate the temporal advantages neuroweapons are designed to create. I argue that the application of contemporary IHL presupposes that cognition is embodied in one single human being and coupled to language. Neuroweapons spread cognition across humans and machines combined, and largely eliminate the cognitive role of language. Both traits render the distinction between superior and subordinate unstable, therewith disrupting the premises of responsibility under IHL. By consequence, it is impossible to assess whether future uses of these weapons are lawful under IHL.