Many studies show that supranational governance structures (SGS)—understood as international organizations or international treaties—contribute to the global diffusion of public policies. However, we still have a limited understanding of which properties of SGS hasten the number of policy adoptions. To advance this literature, we argue that SGS making legally binding and univocal claims are more likely to act as diffusion accelerators. We demonstrate the suitability of this argument through a case study of the global diffusion of mifepristone approvals, a single-purpose medicine to terminate pregnancies that has revolutionized abortion services. The analysis supports our expectation. Links to the EU and the Maputo Protocol—the only two considered SGS that make binding claims with clear implications for this policy field—hasten mifepristone approvals. By contrast, ratification of four other treaties—that do not make binding and univocal claims—and exposure to World Health Organization guidelines on medical abortion does not hasten these approvals.

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超国家治理结构的特性和政策传播：米非司酮批准的案例

许多研究表明，超国家治理结构（SGS）——即国际组织或国际条约——有助于公共政策的全球传播。然而，我们对于 SGS 的哪些特性能够加速政策采用的数量仍然了解有限。为了推进这一文献的发展，我们认为 SGS 做出具有法律约束力和明确的声明更有可能起到扩散加速器的作用。我们通过米非司酮批准在全球传播的案例研究证明了这一论点的适用性，米非司酮是一种终止妊娠的单一用途药物，彻底改变了堕胎服务。分析支持了我们的预期。与欧盟和《马普托议定书》的联系——唯一两个被认为对这一政策领域做出具有约束力声明且对该政策领域具有明确影响的 SGS 协议——加速了米非司酮的批准。相比之下，批准其他四项条约（这些条约没有提出具有约束力和明确的主张）以及了解世界卫生组织关于药物流产的指南并不能加速这些批准。