As wars today involve the use of sophisticated weapons such as autonomous ones, this paper aims to address the moral permissibility of using autonomous weapons systems (AWS) in wars. In the debate on autonomous weapons, advocates argue based on AWS’s precision of targets (Arkin 2018) and it not being clouded by emotional judgments (Marchant, et.al 2011) and prohibitors who comment on the ethical and legal implications of autonomous weapons (A. Sharkey 2019; Blanchard 2022). However, there has been relatively little development of compliance of the autonomous weapons with all the principles of jus in bello, amongst the scholarship as well as its engagement with the just war framework broadly. To assess the moral compliance of AWS, the paper focuses on just conduct or the jus in bello principles. It closely examines all the three principles of necessity, discrimination, and proportionality that makeup just conduct as well as the legal body of International Humanitarian Law (IHL). Through a close analysis of all the principles of jus in bello against the use of autonomous weapons, this paper will result in the incompatibility of such weapons with the ethical framework of just war theory that gives out the norms for just and fair conduct during wars. It will thereby lead to a further reflection on the compliance of autonomous weapons as per jus in bello and the IHL to have greater restrain and ethical conduct during wars.