The purpose of this work is to prove that the theory of constructivism can be an escape from the trap of the constant struggle for influence, which now includes interdisciplinary research combining international law and international relations. For this purpose, the work is divided into three sections. In the first one, the author briefly presents the genesis of in- terdisciplinary research on international law and international relations. In the second part, the sceptical approach of international law researchers towards combined interdisciplinary research is presented. Also in this section, the theory of constructivism is characterised as a potential area for mutual cooperation between international law and international rela¬tions. In the final part, based on the relationship between international humanitarian law and the features of modern weapons, the author tries to prove that the theory of constructiv- ism is perfectly suited to the analysis of contemporary relations between international law and the policies of nations on the international stage.