The application of law and norms in military operations is complex. This article provides an overview of legal and normative aspects in un peace operations. It will focus on key challenges to un peace operations. First, it will review un peacekeeping from the perspective of international law. After providing an overview of the legal framework of un peacekeeping and the application of human rights law, international humanitarian law, and international criminal law, the article turns to issues related to the accountability and immunity of un peacekeepers. The final section addresses normative concepts including the responsibility to protect, the protection of civilians, human security and their relevance in regard to un peacekeeping.