From grey zone to customary international law: How adopting the precautionary principle may help crystallize the due diligence principle in cyberspace

Abstract

The international principle of is well recognized under international law, and is an outgrowth of the general obligation of States to do no harm. The due diligence principle imposes an obligation on States to take affirmative action to ensure their territory or objects over which they maintain sovereign control are not used for internationally wrongful purposes. The due diligence principle has been recognized by international scholars and jurists since the early 20th century, and has been adopted as a principle of customary international law in the international environmental law context by States and courts, including the International Court of Justice. The International Court of Justice has specifically endorsed a procedural aspect of due diligence - that States must conduct environmental impact assessments, where appropriate, as a precautionary measure to ensure their territory is not used for internationally wrongful purposes. In 2013 and 2017, the Tallinn Manual and Tallinn Manual 2.0 confirmed the due diligence principle applies in cyberspace. However, in both manuals, the experts could not agree on the scope of its application. And, in 2017, the Tallinn Manual 2.0 experts agreed that the due diligence obligation does not include a preventive feature, as is reflected in international environmental law. This paper examines this grey area of international law, and whether and to what extent the precautionary principle, as adopted in the international environmental law context, could be applied in cyberspace. After an examination of the precautionary principle as applied, this paper argues its application in cyberspace would help crystallize the due diligence principle from a grey zone in international law into customary international law of cyberspace by introducing a procedural due diligence requirement for States to conduct a cyber impact assessment where appropriate.