As part of a symposium on cyberwar, this invited contribution explores the challenges that new technologies pose for international law. Borrowing from administrative law’s discussion of the “Chevron step-zero” question, the Article argues that weapons-related technological innovation spurs an analogous international law question: Is the new innovation a type of weapon that existing international law can satisfactorily regulate? This is the “international law step-zero” question.

Part I chronicles recent instances in which the “international law step-zero” question has arisen with respect to new technologies and the laws of war, including debates about whether the laws of war can and do regulate nuclear weapons, drones, cyber weapons, and lethal autonomous weapons systems (or “killer robots”). Despite the recurring debates, the answer to the step-zero question often steers toward rejecting fundamental changes to existing laws and regulating new technologies through the application of existing laws, perhaps with tweaks at the margins to accommodate the new technologies’ peculiar features.

Part II focuses on cyber weapons as a case study to explore first, why debates continue to arise with respect to the step-zero question, and second, why the frequent answer is the application of existing laws of war. On the first question, the Article argues that the nature of international law, frequency of weapons development, and incentives of a variety of groups to question the legality of new weapons spark the recurrence of the step-zero question. The Article then identifies several explanations for the recurrence of the application of existing law, including the adaptability of existing laws of war, continuity in the fundamental interests that the laws of war seek to protect, the desire to ensure that weapons are regulated from the time of their first use, and the utility of creating a shortcut to a workable regulatory regime that, at worst, preserves existing disagreements about the laws of war.

Although recognizing that the answer to the step-zero question is generally the application of existing laws of war, this Article does not suggest that no new law is needed for new technologies. Rather, it argues that most law-of-war rules apply most of the time to most new technologies and that any new laws specific to a new technology should generally constitute a comparatively small fraction of the laws of war applicable to that technology. To that end, Part III addresses circumstances in which new law for cyberwar may be necessary and offers several proposals for cyber-specific additions or amendments to existing laws of war.

Kristen Eichensehr, Cyberwar and International Law Step Zero, 50 Texas International Law Journal, 357–380 (2015).
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