The thesis of this article is that the just war theory must be reformulated in such a way that it can be applied to new types of wars. Today, there has been a theoretical shift when discussing the nature of war, encompassing both a change in language and a practical shift. The theoretical shift has brought about a crisis regarding the idea of sovereignty as the notion that orders both internal and international relations. Consequently, other concepts related to the theme of sovereignty have lost their relevance. On the other hand, due to the practical shift, war has been redefined as “a new type of war”. War has become a not entirely overt confrontation of forces supported by various, not always explicit sides in the conflict. The legal aspects of war, responsibility for war and future visions of peace cannot be considered without a sovereign power, a political community and a hierarchy. To date, the just war theory has been the basis of international law concerning war. Contemporary international relations and armed conflicts cannot be governed by the laws of war and ordered by the just war theory. An alternative is therefore emerging: the basis of martial law can be discarded or the just war theory can be reformulated. However, it must be reformulated in such a way that it takes into account the changes that have occurred with respect to sovereignty and forms of political community.