In contemporary armed conflicts States’ armed forces are deployed not only to conduct hostilities against the enemy but also to engage in activities other than military confrontation, such as police operations. If a party to a conflict engages in hostilities, it is obliged to conduct them in accordance with the paradigm of hostilities and to comply with regulations set forth in the law of armed conflict, and if the actions of that party take the form of a police operation, then one should refer to the law enforcement paradigm based on human rights. This text explains that these two paradigms are different in fundamental ways. While complementary, law of armed conflict and human rights law differ in the way in which they regulate the use of lethal force because of the different circumstances in which they were designed to apply: armed conflict and peacetime. This text presents also key definitional elements of both paradigms and indicates when and how they interplay.