The European Union has seen the rise of informal groups of states as an increasingly important governance mechanism within its formal structures. Such groups can make decision-making processes more efficient, but they also suffer from a substantial lack of legitimacy in the eyes of the non-members. In this article, we examine how informal groups overcome this fundamental dilemma between efficiency and legitimacy and sustain themselves at the forefront of important policy areas. To this end, we trace the development of what we argue to be a particularly useful case: the E3 directoire in the nuclear negotiations with Iran. The empirical results point to new insights into how directoires – and informal groups in general – can use different types of legitimation strategies to gain and maintain legitimacy. More specifically, the E3 implemented three successive legitimation strategies – detachment, co-optation and integration – using different types of legitimacy sources, in particular problem-solving, institutional adjustments and fostering institutional and policy congruence.

中文翻译：

---

非正式国家集团的合法化策略：与伊朗进行核谈判中的E3指挥官案例

欧盟已经将非正式国家集团的崛起视为其正式结构中日益重要的治理机制。这样的团体可以使决策过程更有效率，但在非会员看来，他们也缺乏合法性。在本文中，我们探讨了非正式团体如何克服效率和合法性之间的这一根本难题，并在重要政策领域的最前沿保持自己的地位。为此，我们追溯了我们认为是一个特别有用的案例的发展：与伊朗进行核谈判中的E3指挥官。实证结果表明，新的见解表明，指挥机构以及一般的非正式团体如何可以使用不同类型的合法化策略来获得和维持合法性。进一步来说，