Due Diligence in International Law: Cause for Optimism?

Abstract

Due diligence is not a new concept in international law. It has been used to address State conduct in significant transboundary harm, the law of the sea, protection of aliens and violence in the private sphere in human rights law, especially in the context of violence against women. However, the role of due diligence in international law has been questioned -particularly whether it makes primary obligations weaker and whether its usage adds a clear value. This article examines what the role of due diligence is, its potential, and whether there is a reason to be optimistic about the concept in international law. It argues that the potential value of the concept lies in its malleability and capacity to expand what is required of the State in fulfilling its obligations, yet limitation persists because due diligence relies on international courts and tribunals to crystallise what it entails into a hard legal standard.