Since its foundation in 1999 Boko Haram has carried out numerous acts of violence on the territory of Nigeria. The Office of the Prosecutor (OTP) of the International Criminal Court (ICC) has been monitoring the violence between Boko Haram and Nigerian armed forces as part of a preliminary investigation. It has stated that there is reason to believe that Boko Haram is responsible for war crimes and crimes against humanity and that the violence between Boko Haram and the armed forces has reached the level of an armed conflict of non-international character under international law. This paper assesses certain types of behaviour of Boko Haram from an Islamic law perspective and examines whether Islamic law condemns or justifies such acts. Arguably, it would help the ICC in asserting the legitimacy of its judgments, if it was able to prove that such judgments are compatible with the legal and belief system recognised by the actors at trial. In turn it would enable the Court to deal with at least some of the criticism aimed at it, for being an imperialistic institution.