TReView: Visualizing the European Union Transparency Register

The Transparency Register (TR) [9] is a public database established by the European Union (EU) in 2011 and continuously updated since then. It collects information about lobbyists – organizations, companies, and institutions – that seek to influence EU decision-making on specific topics or strategic areas of interest [2, 4, 5, 6]. However, despite the TR aims to enhance transparency by enabling public oversight of meetings between lobbyists and EU officials, the TR’s official website and related systems [3, 8] lack support for advanced data analysis. To address this limitation, we developed TReView, an interactive visual analytics system that employs multiple coordinated views to query and explore TR data from diverse perspectives TReView integrates a temporal view, a multilayer similarity graph view, and a flexible filtering subsystem, allowing users to focus on specific subsets of lobbyists, EU directorates, or topics of interest. The design of TReView has been driven by experts in the legal domain; its effectiveness is demonstrated through selected case studies.

The logical components, data, users, tasks, behind the design of TReView are the following [7].

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  Data. We collected most of the information in the TReView database by a scraping procedure that massively queries the online web site of the TR¹¹1https://transparency-register.europa.eu/searchregister-or-update/search-register_en. We adopted this approach for two main reasons: $(i)$ we could not find public APIs for accessing the TR; $(ii)$ the open data made available by the EU²²2https://data.europa.eu/data/datasets/transparency-register?locale=en (as XML or Excel files) only contains partial information, not updated with the same frequency as the data in the web site.

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  Users. TReView is designed for two main user categories: $(i)$ academic researchers or practitioners, mainly in the fields of legal studies, political science, and sociology, interested in a better understanding of the dynamics of the lobbying activities behind the decision-making process of the EU; $(ii)$ public officials, civil servants, journalists, or civil society activists, interested in investigating specific organizations, persons, or topics, and in discovering potential conflicts of interest in the lobbying activities.

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  Tasks. Following consultations with domain experts in legal studies and sociology, we identified a core set of three macro-tasks that TReView is designed to strongly support: T1 - Data Slicing and Filtering, to focus on specific time windows, lobbyists, organizations, Commission officials or directorates, and meeting topics. T2 - Temporal Analysis, to explore in detail the meetings between lobbyists and Commission officials along the temporal axis. T3 - Similarity Analysis, to recognize clusters of lobbyists that coordinate or behave similarly in terms of meeting topics or fields of interest.

To assess the usefulness of TReView, we conducted two case studies, driven by experts in the legal domain. The first study analyzed the lobbying activities behind the Digital Markets and the Digital Services Acts from December 2020 to December 2022. In addition to offering a clear view of lobbying dynamics, the study revealed a concerning pattern that calls into question the principle of separation of powers – specifically, the divide between legislative and executive branches. The second case studies analyzed the the lobbying dynamics in the automotive sector since the launch of the EU Green Deal strategy on December 2019. It revealed that a high number of EU meetings were held with representative associations of the automotive sector rather than directly with key private companies in the field. Also, a surge in meetings in February 2025 allowed us to discover the promotion of a comprehensive EU strategy aimed to preserve industrial competitiveness and promote decarbonization at the same time. A short video on TReView is available at https://youtu.be/lGq-h2c9GK0.