This essay explores the ethical and legal implications of prioritizing the militarization of cyberspace as part of a roundtable on “Competing Visions for Cyberspace.” Our essay uses an ideal type—a world that accepts warfighting as the prime directive for the construction and use of cyberspace—and examines the ethical and legal consequences that follow for (i) who will have authority to regulate cyberspace; (ii) what vehicles they will most likely use to do so; and (iii) what the rules of behavior for states and stakeholders will be. We envision a world where states would take on a greater role in governance but remain constrained by law, including jus ad bellum and jus in bello criteria, but also sovereignty, nonintervention, and self-determination. We ask if the net result would mean states causing less harm than they do in kinetic conflicts. Ultimately, our essay takes no position on whether cyberspace should be a militarized domain (let alone one where warfighting is the prime directive). Rather, our goal is to situate a warfighting cyber domain within the reality of a pluralist cyberspace, where ethical imperatives compete or coalesce to support specific governance mechanisms.

Does the advent of cyber war require us to abandon the traditional ethical framework for thinking about the morality of warfare – just war theory – and develop principles specific to the unique nature of cyber attacks? Or can just war theory still provide an appropriate basis for thinking through the ethical issues raised by cyber weapons? This article explores these questions via the issue of whether a cyber attack can constitute a casus belli. The first half of the article critically engages with recent attempts to provide a new theory of just information warfare (JIW) that is supposedly better suited to the unique character of cyber war insofar as it is grounded the broader meta-ethical framework of information ethics (IE). Yet the article argues that not only is JIW fundamentally unsuitable as a way of thinking about cyber war, but (in the second half) that it is possible to develop a different account of how we can understand a cyber attack as constituting a casus belli in a way that is in keeping with traditional just war theory. In short, there is no need to reinvent just war theory for the digital age.