So-called “killer robots”, i.e., lethal autonomous weapon systems capable of selecting and attacking military targets without human intervention or control, are a particularly controversial topic in machine ethics. Many prominent AI researchers and scientists are calling for a ban of these devices. The paper will discuss three ethical objections against LAWS: (1) the argument from the responsibility gap (Sparrow), (2) the argument from human agency (Leveringhaus), and (3) the argument from moral duty (Misselhorn). These three arguments raise fundament ethical concerns about LAWS. They are supposed to show that lethal autonomous weapon systems would not just have morally bad consequences but that the use of killer robots is morally wrong in itself.