Although hotly debated, the idea of global justice is a relatively new topic within Anglo-Saxon and Continental political philosophy and theory. This paper discusses when and why Anglo-Saxon political theorists became interested in this field of research. The emergence of cosmopolitan norms of justice after the Second World War is one of these reasons. Subsequently, the paper explains some of the basic concepts that are being used within the field and explains why a political philosophical analysis of the ethical significance of boundaries has an added value for political scientists. The paper concludes by elaborating three different themes within the broad debate on global justice: humanitarian aid, global distributive justice, and democratic representation.