The article analyzes the peculiarities of legal reasoning in final court decisions in cases of violation of the laws and customs of war (Article 438 of the Criminal Code of Ukraine) in the context of such contextual circumstances as the existence of an international armed conflict during which and in connection with which the relevant war crime is committed. The author identifies the following shortcomings in the wording of contextual circumstances in sentences under Article 438 of the Criminal Code of Ukraine: an extensive historical excursion into the historical past of our State and world organizations, as well as the lack of a clear definition of such contextual circumstances. The author proves that in addition to the direct establishment of such circumstances, final court decisions should state the existence of a relevant victim, object and subject of a war crime, which are elements of the mechanism for determining contextual circumstances, as well as independent signs of the crime under Article 438 of the Criminal Code of Ukraine. It is determined that the legal arguments used in final court decisions should include a brief description of the factual and temporal factors of the international armed conflict on the territory of Ukraine, which take place in the country as a whole, as well as the local aspect of the international armed conflict, the existence of which is proved by the occupation of the Ukrainian settlement where the war crime event took place. In addition, when describing the contextual circumstances of the crime under Art. 438 of the Criminal Code of Ukraine, it is advisable to refer to international normative documents and international case law. It is determined that a complete description of the contextual circumstances will ensure the «stability» of court decisions in the courts of appeal, which may be appealed by the defense party arguing that there are no relevant contextual circumstances, which, in the opinion of the defense, indicates that an ordinary crime was committed, rather than a war crime. Key words: war crime, violation of the laws or customs of war, contextual circumstances, international armed conflict, criminal proceedings, international humanitarian law, final judgment, quality of judgment, legal technique, legal reasoning.