We aim to estimate the power distribution in the Council of the European Union—both a priori and a posteriori. With respect to the latter, our analysis suggests that several previously used indices are ill-suited for this application. By introducing minimal modifications, we propose a new index and compare it with previous constructions in a unified framework. Empirically, we find that that all countries gain a priori voting power in the Council as a result of Brexit. We rely on data from the Chapel Hill Expert survey to compute a posteriori power and find that it is more unequally distributed than a priori power. Specifically, a posteriori power is almost exclusively held by relatively few rather populous states (yet not the United Kingdom). As regards Brexit, France appears as the main benefactor in terms of gaining a posteriori power; Poland loses substantive power in several areas but remains one of the most powerful EU member states.

我们旨在估算先验和后验的欧洲联盟理事会权力分布。关于后者，我们的分析表明，一些以前使用的索引不适用于此应用程序。通过引入最少的修改，我们提出了一个新的索引，并将其与统一框架中的先前结构进行比较。根据经验，我们发现，由于英国退欧，所有国家都在安理会获得了先验投票权。我们依赖于Chapel Hill专家调查的数据来计算后验能力，发现它比先验能力更不均匀地分布。具体而言，后验力量几乎完全由相对少数人口众多的州（但不是英国）拥有。关于英国脱欧，就获得后方力量而言，法国似乎是主要的恩人。