We shall introduce some basic ideas that may be useful to approach the discussion on autonomous systems, from a legal perspective, and apply it to autonomous weapons. First of all, we shall distinguish the concepts of automaticity, autonomy, and teleology. We shall then discuss the idea of a cognitive delegation to autonomous systems, considering what aspects of cognition it may concern. We shall also address more specific and extensive notions of autonomy, such as the idea of normative and moral autonomy. Furthermore, we shall extend our discussion to include multi-agent, coordinated, and self-organising systems, by exploring the notion of multi-level autonomy. Finally, we shall consider what liabilities may be involved in the use of autonomous systems.