Autonomous Weapons Systems and the Martens Clause between Ethics and Law

To count as autonomous, a weapons system must be able to select and engage targets without any human intervention after its activation. The fact that, thanks to the recent developments in robotics and AI, the realization of such systems will be increasingly common raises a major ethical and legal issue: Is it is permissible to let a robotic system unleash destructive force and take attendant life-or-death decisions without any human intervention? The present contribution will examine this issue through the lens of the Martens Clause. After some introductory remarks on the Clause, we will address in detail the way they have been invoked in the discussion on autonomous weapons systems (AWS). In this respect, a distinction will be made between two argumentative strands, one focusing on the rights of targeted people, the other zooming in on the duties of the people deciding to use AWS. It will be argued that the latter strand, which ultimately revolves around the ethical unacceptability of the removal of human agency from decisions relating to the use of (lethal) force, is more apt to demonstrate that autonomy in weapons system is a malum in se. This finding will be bolstered by showing that a growing consensus has been gathering within the international community at large (i.e. including the global civil society and private tech sector) as to the need to preserve human agency in decision-making processes that may affect individual rights.