The customary law duty to prevent significant transboundary harm and harm to the global commons (‘no-harm’ rule) has developed considerably since it was first enunciated in the 1938/1941 Trail Smelter arbitration. This article reflects on this development and analyses what implications the 2015 Certain Activities case has for existing understandings of the no-harm rule. The International Court of Justice (ICJ)'s judgment provides greater clarity concerning procedural obligations flowing from the no-harm rule by establishing a positive obligation to ascertain risk and a sequence in which procedural obligations arise. However, it raises questions concerning the nature of the substantive obligation under the no-harm rule. Specifically, whether breach of the substantive obligation is subject to establishing that an activity has resulted in significant transboundary harm. The ambiguity in the Certain Activities case highlights the need to further clarify and develop the content of the no-harm rule to better enable it to contribute to the governance of contemporary transboundary and global environmental problems.

中文翻译：

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某些活动1案例：对无害规则有何影响？

自从1938/1941年Trail Smelter仲裁中首次阐明习惯税法以来，防止重大跨界损害和对全球公地造成损害的习惯法义务（“无害”规则）已经得到了很大发展。本文对这一发展进行了反思，并分析了2015年某些活动案对现有对无害规则的理解的含义。国际法院（ICJ）的判决通过确立确定风险的积极义务和产生程序义务的顺序，更加明确了从无损害规则产生的程序义务。但是，它提出了关于无害规则下实质义务性质的疑问。具体来说，违反实质性义务是否应确定某项活动已造成重大跨界损害。“某些活动”案例中的含糊之处突出表明，有必要进一步阐明和发展无害规则的内容，以使其能够更好地为当代跨界和全球环境问题的治理做出贡献。