International water law principles in negotiations and water diplomacy

International water law (IWL) principles are often called upon to address disagreements and conflict between riparian states to a shared watercourse, with various parties invoking them to guide states’ behavior towards cooperative solutions that benefit the water resources as well as broader regional cooperation and peace. This essay argues that it is particularly important to acknowledge the role IWL principles play in negotiation processes, that is, in an ex ante and non-judicial function, providing a framework for cooperation and contributing to lawmaking, which makes them important tools of international relations and water diplomacy. First, IWL principles are particularly relevant in negotiation processes. IWL principles are thus not only relevant to legal adjudication or enforcement, but are also tools of international relations and diplomacy. Additionally, in their ex ante role, in the context of negotiations or other non-judicial interactions between riparian states, IWL principles can pose an inherent dilemma, as they can both provide a framework for negotiations and be the focus of negotiations, each dimension having implications for the effectiveness of negotiations and the likelihood of negotiated compromise outcomes. Third, in spite of this inherent dilemma and its possible negative repercussions on negotiation outcomes, the use of IWL principles in negotiations has a lawmaking function, contributing to the further development and strengthening of the overall legal regime for governing shared watercourses