In international peace operations, Swedish and other countries' military units follow so-called Rules of Engagement (ROE). These are based on legal but also political and military operational considerations. International and national law sets the external framework for ROE, which regulates the use of force and violence, e.g. to protect the civilian population in a conflict zone. The ultimate aim of the project is for staff to know that they have legal support to apply the rules that governments have directly or indirectly accepted. As a command and control instrument, the rules of engagement are often decided at a high strategic level by the organisation responsible for the peacekeeping force, which leads the operation under a mandate from the UN. To some extent, participating countries can influence the ROE. Soldiers, sailors and airmen, who have no influence, assume that the rules of engagement cover all considerations (and are within the scope of international and national law) and that applying them is generally sufficient. Since the view of ROE seems to be different, there is uncertainty about this and the project therefore aims to investigate and discuss the legal status of ROE in peace operations in Sweden and in other Nordic countries that contribute with personnel. Instead of focusing on substantial but often secret rules in detail, the project deals with process-related issues such as how the rules of engagement come about, how they are accepted and what weight these rules have or should have.