The first case before the international court of justice discussed the principle of due diligence, described by the court as the well-established obligation not to allow knowingly its territory to be used for acts contrary to the rights of other States.
This thesis discusses the principle of due diligence in general in international law, describing an obligation which varies between areas of law. Thereafter the findings are applied to the cyber-domain, and a study of the current state of the principle of due diligence in international law is conducted. Finally, the thesis applies the findings, both in general international law and international law applicable to cyber operations, to the cyber-attacks on Estonia in 2007 and Germany 2020 respectively. In light of this the thesis emphasises the need for accountability in international law, and describes the difficulties of regulating conduct in the cyber-domain.