With the surge of populism worldwide, many observers have become increasingly concerned about the erosion of the rule of law. While scholars have primarily focused on democratic backsliding in salient cases like Hungary or Poland, where populist parties formed a government, we know much less about the strategies of populist parties in opposition. We argue that populist politicians use social media to systematically de-legitimize the judiciary. Parallel to the rise of populism, the increasing popularity of social media as a political communication tool has enabled politicians to circumvent traditional media. The disruption of the media landscape disproportionately benefits populists who were previously most constrained by media gatekeepers. To empirically test our argument, we scrutinize the elite discourse concerning the rule of law in Poland, Germany, The Netherlands, and the United Kingdom. We collected data on 166,140 Twitter posts concerning the judicial system by MPs in the four countries between 2013 and 2022. To categorize social media posts, we train and validate BERT-based models on manually coded textual data. Afterward, we examine how MP's social media communication varies across political parties with respect to tone (neutral, positive, negative) and target (judicial system, constitution, court, judge, decision).
