Update to revolving door 2.0: The extension of the period for direct participation in hostilities due to autonomous cyber weapons

The rule concerning the direct participation in hostilities (DPH) by civilians is one of the most controversial rules within the law of armed conflict. While civilians are generally guaranteed protection by the principle of distinction, DPH provides for a loss of protection ‘for such time as they take a direct part in hostilities’. This temporal component of DPH poses significant challenges in light of the use of autonomous cyber weapon systems (ACWS), as the active part of the civilian can be reduced to the second of activation. Autonomy in this context means that the ACWS is able to operate without any human control, rendering human influence on the actions impossible. As soon as the ACWS is fully selfoperating, the common interpretation based on the original wording of the DPH-rule would suggest that DPH is no longer possible. Consequently, a civilian hacker using ACWS cannot lawfully be attacked after control of the system has been relinquished even if damage occurs or the attack is recognised later. As a result, civilian hackers are legally privileged without any discernible justification. In order to remedy this unsatisfactory situation, this article suggests an extension of the relevant period of time for DPH to the whole period of the operation of the ACWS to solve the ‘Revolving Door 2.0’ problem. It is further submitted that concerns that such an extension would unduly broaden the scope of the DPH-rule can be met by the requirement that, additionally, the regular cumulative criteria for DPH have to be fulfilled.