While the law of neutrality was developed in an era predating the modern jus contra bellum (where the broader notion of "armed conflict" was not yet in use), this chapter argues that the law of neutrality has survived the legal developments of international law in the 20th century and still forms a relevant body of law today. However, the law of neutrality fails to present a clear answer to all the legal questions posed by 21st century warfare. After a short preliminary note on the legal concept of neutrality, this chapter starts by discussing the origins of the law of neutrality and its codification. Subsequently, the applicability of the law of neutrality is dealt with, followed by an overview of the rights and duties of neutral States in light of the UN Charter. This chapter then explains how the legal framework of the EU has posed challenges to neutrality law, and investigates the arguments in favour of and against an intermediate status of non-belligerency. Finally, it provides some examples showing that the law of neutrality is not dead in today's world of modern conflict.