The duty to prevent significant transboundary harm remains a cornerstone principle of international law, and especially of international environmental and water resources law. However, this rule focuses on the conduct of a State where harm originates, rather than on the fact that harm has resulted from such conduct, and thus requires that States exercise due diligence in anticipating and in preventing or mitigating such harm. At a practical level, the due diligence standard of conduct expected of States can be uncertain and difficult to determine, as it must be deduced from the applicable primary rules of international environmental or water resources law, which have traditionally been elaborated in rather vague terms. In addition, the standard of due diligence required under the no-harm rule may be influenced by a range of variable and context-specific factors which might prove relevant in the particular circumstances of any dispute. Such uncertainty is further compounded in the field of international water law by the complex interrelationship between the no-harm rule and the other key norms of international water law, particularly the cardinal principle of equitable and reasonable utilization, which embodies a high degree of flexibility and adaptability and suffers from a corresponding degree of normative indeterminacy. Thankfully, recent developments in international water law and related practice regarding the requirement to protect riverine ecosystems and maintain related ecosystem services lend a welcome measure of clarity as regards the preventive measures expected of watercourse States under international law. Judicial recognition of obligations to maintain minimum environmental flows and to preserve or restore riverine ecosystem services, based on the proliferation of such values in treaty and declarative practice, along with the continuing development of sophisticated technical methodologies for ecosystems assessment and evaluation, do much to inform the due diligence conduct required of States. Such advances can only enhance the practical utility of the no-harm rule, and thus of the entire corpus of international water law, in addressing the challenges emerging globally for water resources management in the twenty-first century.

中文翻译：

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无重大伤害原则的发展现状：我们走了多远？

防止重大跨界损害的义务仍然是国际法，尤其是国际环境和水资源法的基石原则。然而，该规则侧重于损害起源国的行为，而不是损害由此类行为造成的事实，因此要求各国在预测和预防或减轻此类损害方面尽职尽责。在实践层面，预期各国的尽职调查标准可能不确定且难以确定，因为它必须从适用的国际环境或水资源法的主要规则中推导出来，而这些规则传统上是用相当模糊的术语阐述的。此外，无损害规则所要求的尽职调查标准可能受到一系列可变因素和特定背景因素的影响，这些因素可能与任何争议的特定情况相关。无害规则与国际水法的其他关键规范，特别是公平合理利用的基本原则之间的复杂相互关系，进一步加剧了国际水法领域的这种不确定性，它体现了高度的灵活性和适应性并遭受相应程度的规范不确定性。谢天谢地，国际水法和有关要求保护河流生态系统和维持相关生态系统服务的相关实践的最新发展为国际法规定的水道国采取的预防措施提供了一种可喜的明确措施。司法承认维持最低环境流量和保护或恢复河流生态系统服务的义务，基于条约和声明实践中此类价值的扩散，以及生态系统评估和评价的复杂技术方法的不断发展，对提供信息有很大帮助各国要求的尽职调查行为。这种进步只会提高无害规则的实际效用，从而提高整个国际水法的实际效用，