The article deals with the core area of the Just War discipline, which is the set of criteria for deciding whether the start of war can be regarded as just or unjust. It presents the six most frequently mentioned criteria and offers a critical commentary on the content and meaning. By thoroughly studying over forty selected sources of Czechoslovak origin, it captures the current state of discussions in the area and simultaneously documents the fragmentation of fundamental terminology. Therefore, it also presents an argument-based proposal for the most appropriate Czech language terms of the mainstream criteria, aiming to unify the lexical field of the Just War discipline in the Czech academic discourse.