s US foreign policy observers have noted a decline in the frequency of expert witnesses appearing before congressional committees, while congressional scholars have documented changes in committee practices that have led to fewer and shorter hearings. These trends interact in systematic ways, although their relationship has never been tested empirically. Using original data and micro-level measures of individual hearings by the national security committees of the House and Senate, we demonstrate how time constraints and routine responsibilities limit the number of opportunities for expert witnesses from 1995 to 2020. We find some influence for chamber polarization on witness totals but less impact on the type of experts. We uncover significant differences among individual committees in their use of academics and think tank representatives. Our study is unique in its focus on both chambers, inclusion of closed hearings, differentiation between academics and think tank representatives, and attention to the public salience of foreign affairs. Shrinkage in the official marketplace of foreign policy ideas warrants concern, highlighting the executive branch's increasing dominance over military and diplomatic decisions, diminished legislative capacity, and public disinterest in international affairs.

中文翻译：

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所有专家都去哪儿了？国会山外交政策思想的转变市场


的美国外交政策观察家注意到专家证人在国会委员会出庭的频率有所下降，而国会学者则记录了委员会做法的变化，这些变化导致听证会越来越少。这些趋势以系统的方式相互作用，尽管它们之间的关系从未经过实证检验。使用众议院和参议院国家安全委员会个人听证会的原始数据和微观衡量标准，我们展示了从 1995 年到 2020 年，时间限制和日常责任如何限制专家证人的机会数量。我们发现众议院两极分化对证人总数有一定影响，但对专家类型的影响较小。我们发现各个委员会在使用学者和智库代表方面的显着差异。我们的研究在关注两院、包括闭门听证会、区分学术界和智库代表以及关注外交事务的公众重要性方面都是独一无二的。外交政策思想官方市场的萎缩令人担忧，凸显了行政部门对军事和外交决策的主导地位日益增强，立法能力下降，以及公众对国际事务的不感兴趣。