International organizations promoting democratic governance and human rights are increasingly challenged by some of their own member states. To better understand this dynamic, we propose a distinction between the illiberal ideology of political parties and their regime environment, aiming to examine the international behavior of actors extending beyond autocratic governments. We argue that the domestic regime environment plays a pivotal role in influencing the extent to which illiberal parties engage in contestation to undermine liberal norms on the international stage. We expect contestation behavior to be primarily driven by illiberal parties seeking to diminish the influence of liberal international politics on domestic power structures. Moreover, we contend that government participation moderates illiberal parties’ contestation behavior. To test our expectations empirically, we study roll call votes in the Parliamentary Assembly of the Council of Europe (PACE), one of the most powerful international parliaments promoting liberal values. Drawing on an original dataset that records approximately 500,000 individual votes cast in PACE decisions, we find evidence for substantive contestation by illiberal parties, especially those representing illiberal regimes. Only illiberal governments in liberal systems moderate themselves at the amendment stage. Our study has implications for the potential threat that emerging illiberal actors pose to international liberal institutions.

促进民主治理和人权的国际组织日益受到一些成员国的挑战。为了更好地理解这种动态，我们提出区分政党的非自由意识形态及其政权环境，旨在研究超越独裁政府的行为体的国际行为。我们认为，国内政权环境对于影响非自由政党在国际舞台上参与破坏自由规范的争论程度发挥着关键作用。我们预计，竞争行为将主要由寻求削弱自由国际政治对国内权力结构影响的非自由政党推动。此外，我们认为政府参与可以缓和非自由政党的竞争行为。为了从实证上检验我们的期望，我们研究了欧洲委员会议会大会 (PACE) 的点名投票，欧洲委员会议会是促进自由价值观的最强大的国际议会之一。利用记录了 PACE 决策中大约 500,000 个人投票的原始数据集，我们找到了非自由政党，特别是代表非自由政权的政党进行实质性争论的证据。只有自由体系中的非自由政府才会在修正阶段自我节制。我们的研究对新兴非自由行为者对国际自由主义机构构成的潜在威胁具有影响。