International institutions strive to achieve their own objectives while operating within a complex network of interdependencies. These interdependencies create an extensive web of relationships that serve as potential pathways for broader institutional impacts. The actions taken by individual institutions, their mutual influences, and the pattern of connectivity collectively shape the overall performance of institutional complexes. Understanding the performance of these complexes is crucial, yet we currently lack a methodology to assess it. To address this gap, we have developed a conceptual framework that integrates three distinct areas of study on three different scales: institutional effectiveness, institutional interlinkages, and institutional networks. This framework enables us to consider what we call the latent net effectiveness, or collective problem-solving potential, of a group of interconnected institutions. To put this framework into practice, we have devised a heuristic model, drawing from the extensive literature on international environmental institutions. As an illustrative example, we have applied this model to a network of 378 multilateral environmental agreements with 810 known issue linkages. Our work underscores the relevance of considering the system-level properties of institutional complexes and emphasizes the need for timely network-based governance and policy interventions to enhance the overall effectiveness of institutional complexes.

This article is part of the theme issue ‘A complexity science approach to law and governance'.

国际机构在相互依存的复杂网络中运作时，努力实现自己的目标。这些相互依存关系创造了一个广泛的关系网络，成为产生更广泛的制度影响的潜在途径。各个机构采取的行动、它们之间的相互影响以及连通性模式共同塑造了机构综合体的整体绩效。了解这些复合体的性能至关重要，但我们目前缺乏评估它的方法。为了解决这一差距，我们制定了一个概念框架，整合了三个不同尺度的三个不同研究领域：机构有效性、机构相互联系和机构网络。这个框架使我们能够考虑一组相互关联的机构的潜在净有效性或集体解决问题的潜力。为了将这一框架付诸实践，我们借鉴了有关国际环境机构的大量文献，设计了一个启发式模型。作为一个说明性的例子，我们已将此模型应用于由 378 个多边环境协定组成的网络，其中包含 810 个已知问题联系。我们的工作强调了考虑机构综合体的系统级属性的相关性，并强调需要及时基于网络的治理和政策干预，以提高机构综合体的整体有效性。

本文是主题“法律和治理的复杂性科学方法”的一部分。