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Mr. P.J. (Paddy) Leerssen LLM

Faculty of Law
Information Law
Visiting address
  • Nieuwe Achtergracht 166
Postal address
  • Postbus 15514
    1001 NA Amsterdam
Contact details
  • Publications

    2026

    2024

    2023

    2021

    • Leerssen, P. J. (2021). Platform research access in Article 31 of the Digital Services Act. In R. Heiko, S. Marlene, & T. Erik (Eds.), To Break Up or Regulate Big Tech? Avenues to Constrain Private Power in the DSA/DMA Package (pp. 55-61). Max Planck Institute for Innovation and Competition. https://ssrn.com/abstract=3932809

    2020

    2019

    2015

    2025

    • Albert, J. A., & Leerssen, P. J. (2025). Workshop Report: Researchers on Data Access and Preparing for DSA Article 40(4). Web publication or website, DSA Observatory.
    • Irion, K., Leerssen, P. J., & Metikoš, L. (2025). Het inzagerecht ex art. 15 AVG en het beroep op gerechtvaardigde belangen, met name de bescherming van bedrijfsgeheimen en platformbeveiligingssystemen. Instituut voor Infomatierecht.
    • van Duin, J. M. L., Leerssen, P. J., van Hoboken, J. V. J., & Toepoel, I. S. (2025). Pathways to Private Enforcement of the Digital Services Act (DSA). https://dsa-observatory.eu/2025/06/05/report-pathways-to-private-enforcement-of-the-digital-services-act-dsa/

    2024

    2023

    2022

    2021

    2020

    2019

    2015

    2014

    2026

    2024

    • Leerssen, P. (2024). Shadow banning op X. 8. Case note on: Rb. Amsterdam, 5/07/24, ECLI:NL:RBAMS:2024:3980 (Twitter). Mediaforum, 36(4), 131-136. [details]

    2023

    2022

    • Leerssen, P. J. (2022). Computerrecht 2022/97. 97. Case note on: Rb. Noord-Holland, 6/10/21, C/15/319230 / KG ZA 21-432, ECLI:NL:RBNHO:2021:8539 (Kamerlid tegen LinkedIn). Computerrecht, 2022(3), 223-230. [details]

    2021

    2020

    2019

    2016

    Prize / grant

    • Leerssen, P., van Duin, A., van Hoboken, J. & Trogrlić, G. (2026). Luminate Foundation Research Grant (Phase 2).
    • Leerssen, P. & van Hoboken, J. (2026). Onderzoek wettelijke minimumleeftijd sociale media.
    • van Hoboken, J., Leerssen, P. & van Duin, A. (2024). Luminate Foundation Research Grant.
    • Ausloos, J., Leerssen, P. & Khanna, S. (2024). ARILS Methods and Interdisciplinary Research Fund.
    • Leerssen, P. (2023). DTDM Seed Funding Grant.
    • Helberger, N., Ausloos, J. & Leerssen, P. (2020). Commissioned to write a report for Algorithm Watch, Platforms and Transparency.

    Membership / relevant position

    Media appearance

    Journal editor

    • Leerssen, P. (editor) (2023-2025). Mediaforum (Journal).

    Talk / presentation

    • Leerssen, P. (invited speaker) (19-4-2026). Expert Briefing on Demotion and Shadowbanning, Meta Oversight Board.
    • Leerssen, P. (invited speaker) (9-4-2026). Outside the (black) box: From algorithmic transparency to platform observability in the Digital Ser-vices Act (DSA)., Georgetown - Harvard Data Co-ops Project.
    • Leerssen, P. (invited speaker) (11-3-2026). From Murdoch to Musk: Platform ownership and the political economy of content moderation, Columbia-Hertie Speaker Series on Digital Governance for Democratic Renewal.
    • Leerssen, P. (invited speaker) (4-3-2026). From Murdoch to Musk: Platform ownership and the political economy of content moderation, Conservatoire National des Arts et Métiers .
    • Leerssen, P. (keynote speaker) (16-2-2026). Shareholders’ Values: Platform Regulation and Tech Oligarchy, DSA and Platform Regulation Conference 2026, Amsterdam.
    • Leerssen, P. (invited speaker) (10-10-2025). Pathways to private enforcement of the DSA, Euroconsumers RE-ACT PILOT Training Session.
    • Leerssen, P. (invited speaker) (5-10-2025). From Murdoch to Musk: Platform ownership and the political economy of content moderation, Ministry for the Presidency of Spain, Centro do Estudios Políticos Y Constitucionales (CEPC), .
    • Leerssen, P. (speaker) (27-9-2025).  From Murdoch to Musk: Platform ownership and the political economy of content moderation, European Law Unbound Society (ELU-S) Annual Conference, Prague.
    • Leerssen, P. (speaker) (4-6-2025). From Murdoch to Musk: Platform ownership and the political economy of content moderation, AoIR Flashpoint Symposium.
    • Leerssen, P. (speaker) (24-5-2025). Approaches to DSA data access, CPDP 2024, Brussels.
    • Leerssen, P. (speaker) (13-5-2025).  Outside the (black) box: From algorithmic transparency to platform observability in the Digital Ser-vices Act (DSA), SciencesPo Conference on Algorithmic Transparency and the Digital Rule of Law.
    • Leerssen, P. (invited speaker) (10-4-2025). Content Moderation and/as Propaganda: Four Lessons from Propaganda Studies for Online Content Regulation, University of Brest.
    • Leerssen, P. (invited speaker) (9-4-2025). The Political Economy of Content Moderation., University of Brest Spring Course on Social Media.
    • Leerssen, P. (invited speaker) (2-4-2025). From Murdoch to Musk: Platform ownership and the political economy of content moderation, Wissenschaftszentrum für Sozialforschung Berlin (WZB).
    • Leerssen, P. (invited speaker) (1-4-2025). From Murdoch to Musk: Platform ownership and the political economy of content moderation, Weizenbaum-Institut für die vernetzte Gesellschaft.
    • Leerssen, P. (invited speaker) (29-11-2024). The Political Economy of Content Moderation, Digital Legal Talks 2024, Utrecht.
    • Leerssen, P. (speaker) (28-11-2024). PLSC Session: Regulating pressing systemic risks – but not too soon? Comparative Analysis of the Implementation of Data Access Requests to Platform Data under Article 40(4) of the EU Digital Services Act, Digital Legal Talks 2024, Utrecht.
    • Leerssen, P. (invited speaker) (19-11-2024). European Commission Webinar on DSA delegated act on data access, European Commission.
    • Leerssen, P. (invited speaker) (8-11-2024). The Political Economy of Content Moderation, Digital Legal Talks 2024, Utrecht.
    • Leerssen, P. (invited speaker) (9-10-2024). De DSA en desinformatie, Symposium Brinkhof Internetscriptieprijs.
    • Leerssen, P. (invited speaker) (24-9-2024). Seeing outside the (black) box: From algorithmic transparency to platform observability in the Digital Services Act, Hertie School of Governance.
    • Leerssen, P. (invited speaker) (26-6-2024). Systemic Risks under the DSA, European Rights & Risks: Stakeholder Engagement Forum.
    • Leerssen, P. (invited speaker) (11-6-2024). Expert governance in the DSA, SciencesPo DSA & Free Expression Workshop.
    • Leerssen, P. (invited speaker) (10-6-2024). Expert Governance in the DSA, SciencesPo Workshop on the DSA and Freedom of Expression.
    • Leerssen, P. (speaker) (6-6-2024). The Political Economy of Content Moderation, Conflicts and Communities: SciencesPo Young Digital Law Conference.
    • Leerssen, P. (invited speaker) (4-5-2024). Private enforcement of the DSA, CDT Civil Society Roundtable.
    • Leerssen, P. (invited speaker) (19-3-2024). Expert Briefing on Demotion, Meta Oversight Board.
    • Leerssen, P. (speaker) (19-3-2024). The Digital Services Act, Vrije Universiteit (VU).
    • Leerssen, P. (invited speaker) (24-1-2024). Leiden University Workshop on Disinformation and Human Rights in Context - Panel I The Media, Online Platforms and Emerging Technologies, Leiden University Workshop on Disinformation and Human Rights in Context.
    • Leerssen, P. (invited speaker) (15-1-2024). LSE Digital Accountability Workshop, LSE Digital Accountability Workshop
      .
    • van Eechoud, M. (invited speaker), Janssen, H. (invited speaker) & Leerssen, P. (invited speaker) (5-12-2023). “EU Data governance regulation and academic access to non-public data”, Digital Legal Lab’s winter school “Data, personalization, and the law 2023. https://www.sectorplandls.nl/wordpress/wp-content/uploads/2023/11/Draft-programme-Winter-School-28112023-2.pdf
    • Leerssen, P. (speaker) (9-10-2023). Desinformatie en de DSA, Kritische mening of opzettelijk nepnieuws?
      .
    • Leerssen, P. (invited speaker) (27-9-2023). Seeing outside the (black) box: From algorithmic transparency to platform observability in the Digital Services Act, Hertie School.
    • Leerssen, P. (speaker) (27-9-2023). Seeing outside the (black) box: From algorithmic transparency to platform observability in the Digital Services Act, Hertie School of Governance.
    • Leerssen, P. (speaker) (8-9-2023). Angry nerds: content creators, community moderation and corporate control in Magic the Gathering, GIKII Conference 2023.
    • Leerssen, P. (speaker) (8-9-2023). Angry nerds: content creators, community moderation and corporate control in Magic the Gathering, GIKII Conference 2023.
    • Leerssen, P. (invited speaker) (19-6-2023). Media Law Resource Center Conference 2023, Media Law Resource Center Conference 2023.
    • Leerssen, P. (speaker) (23-5-2023). REGULATED SELF-REGULATION FOR PLATFORM GOVERNANCE AND CONTENT MODERATION, ADM+S BIRMINGHAM WORKSHOP: Standards and assurance for data-driven technologies
      .
    • Leerssen, P. (speaker) (4-5-2023). De DSA en desinformatie, Beeld & Geluid Rondetafel Desinformatie.
    • Leerssen, P. (speaker) (4-4-2023). Outside the (Black) Box: From Algorithmic Transparency to Platform Observability in Social Media Regulation, Platform Governance Research Network (PlatGovNet) conference.
    • Leerssen, P. (speaker) (1-2-2023). The role of National Regulatory Authorities in the Digital Services Act, The role of National Regulatory Authorities in the Digital Services Act.
    • Leerssen, P. (speaker) (13-6-2022). Transparency in the Digital Services Act, European Media Lawyer's Conference 2022.
    • Leerssen, P. (speaker) (29-5-2022). An End To Shadow Banning? Transparency rights in the Digital Services Act between content moderation and curation, the 72nd annual conference of the International Communication Association (ICA), 26-30 May 2022, Paris, France.
    • Leerssen, P. (speaker) (20-5-2022). News from the ad archive: how journalists use the Facebook Ad Library to hold online advertising accountable, Global Conference on Transparency Research, Copenhagen.
    • Leerssen, P. (speaker) (11-5-2022). An end to shadow banning? Transparency rights in the Digital Services Act between contet moderation and curation, DIMACS Workshop on Computer Science & Law.
    • Leerssen, P. (speaker) (13-12-2021). Intermediary Liability & Platform Responsibility, University of Utrecht.
    • Leerssen, P. (speaker) (8-12-2021). Shadow banning, downranking and other secret sanctions: on the transparency of non-takedown content moderation., Digital Legal Talks.
    • Leerssen, P. (speaker) (26-11-2021). Workshop on DSA and fundamental rights, EuroISPA.
    • Leerssen, P. (speaker) (15-10-2021). Adhoc DSA/DMA Working Group on "must carry obligations" of editorial content, European Parliament, Greens/EFA.
    • Leerssen, P. (speaker) (22-9-2021). News from the ad archive: on journalistic usage of the Facebook Ad Library, Future of Journalism Conference.
    • Leerssen, P. (speaker) (7-9-2021). The Soap Box as a Black Box: Regulating Transparency in Social Media Recommender systems, ECREA 2021.
    • Leerssen, P. (speaker) (1-9-2021). Regulation of and by recommender systems, Bilgi IT Law Institute International Summer School on AI.
    • Leerssen, P. (speaker) (24-6-2021). Transparency in ranking algorithms and recommender systems, Center for Democracy and Technology (CDT) Lunch Talk Series.
    • Leerssen, P. (speaker) (22-6-2021). Safeguards for freedom of expression in the regulation of algorithmic ranking and recommendations, Parliamentary Assembly of the Council of Europe, Committee on Culture, Science, Education and Media.
    • Leerssen, P. (invited speaker) (22-6-2021). Safeguards for freedom of expression in the regulation of algorithmic ranking and recommendations, Parliamentary Assembly of the Council of Europe, Committee on Culture, Science, Education and Media.
    • Leerssen, P. (speaker) (25-3-2021). News from the ad archive: on journalistic usage of the Facebook Ad Library, First Annual Conference of a Platform Governance Research Network .
    • Leerssen, P. (invited speaker), Appelman, N. (invited speaker) & Sax, M. (speaker) (17-12-2020). Platform Monopolies, Conglomerates and The Digital Markets Act,
      PEPTalk #1: Big Tech Platform Power Regulation
      .
    • Leerssen, P. (speaker) (2-12-2020). News from the archive: an empirical study of ad archive journalism, Digital Legal Talks.
    • Leerssen, P. (speaker) (26-11-2020). The Soap Box as a Black Box: Regulating Transparency in Social Media Recommender Systems, VSNU Digital Society Conference 2019.
    • Leerssen, P. (invited speaker) (17-11-2020). Transparency in Recommender Systems, Transparency of algorithms: Breaking the Black Box (Hosted by Alexandra Geese MEP). https://en.alexandrageese.eu/digital-platform-digital-services-act-dsa-special/
    • Leerssen, P. (speaker) (5-11-2020). IGF Glossary Project: defining platform governance, Internet Governance Forum (IGF) 2020.
    • Leerssen, P. (speaker) (20-4-2020). The Soap Box as a Black Box: Regulating Transparency in Social Media Recommender Systems, At the Crossroads: Towards a new European Communication Framework?.
    • Leerssen, P. (speaker) (2-2-2020). The Soap Box as a Black Box: Regulating Transparency in Social Media Recommender Systems, Leuven AI Law & Ethics Conference.
    • Leerssen, P. (speaker) (18-10-2019). Platform ad archives: promises and pitfalls, European Advisory Group of Social Science One Workshop: Removing Barriers to Digital Platform Transparency across Europe.

    Others

    • van Hoboken, J. (consultant) & Leerssen, P. (consultant) (2-10-2026 - 30-11-2026). In-house Training Digital Services Act (DSA), Autoriteit Consument & Markt (ACM) (consultancy).
    • Leerssen, P. (organiser), van Hoboken, J. (organiser) & Albert, J. (organiser) (29-6-2026 - 4-7-2026). IViR Summer Course on European Platform Regulation 2026. IViR Summer Course on European Platform Regulation 2026 (organising a conference, workshop, ...).
    • Albert, J. (organiser) & Leerssen, P. (organiser) (20-3-2026). Webinar: Reflections on Art. 40 DSA data access requests (organising a conference, workshop, ...).
    • Albert, J. (organiser), van Hoboken, J. (organiser), Helberger, N. (organiser), Jóźwiak, M. (organiser), Ó Fathaigh, R. (organiser) & Leerssen, P. (organiser) (16-2-2026 - 17-2-2026). DSA and Platform Regulation Conference 2026, Amsterdam (organising a conference, workshop, ...). https://dsa-observatory.eu/conference-2026/
    • Leerssen, P. (organiser) (9-9-2025). DSA Observatory and People v Big Tech Workshop on DSA Litigation 2025 (organising a conference, workshop, ...).
    • Leerssen, P. (organiser) & Seipp, T. (organiser) (5-8-2025). Spui25 Panel on The Rising Power of Big Tech (organising a conference, workshop, ...).
    • Albert, J. (organiser), van Hoboken, J. (organiser), Leerssen, P. (organiser) & Albert, J. (participant) (30-6-2025 - 4-7-2025). 2025 IViR Summer Course on European Platform Regulation (organising a conference, workshop, ...).
    • Leerssen, P. (participant) (23-5-2025). Computer Privacy & Data Protection Conference, Brussels. Panel: Researcher Access in the DSA: State of Play and Next StepsThe Digital Services Act (DSA) contains ambitious new rules for researchers to (…) (participating in a conference, workshop, ...).
    • Leerssen, P. (organiser), van Duin, A. (organiser) & van Hoboken, J. (organiser) (15-5-2025). DSA Observatory Workshop on Private Enforcement (organising a conference, workshop, ...).
    • Albert, J. (organiser), Jóźwiak, M. (organiser), Leerssen, P. (organiser) & van Hoboken, J. (organiser) (28-3-2025). DSA Observatory Joint Workshop on Risk Management andResearchers’ Data Access under the DSA (organising a conference, workshop, ...).
    • Leerssen, P. (participant) (9-12-2024). European Commission DSA Data Access Roundtable, Brussels. Expert policy workshop with European Commission, academic researchers and big tech industry representatives. (participating in a conference, workshop, ...).
    • Leerssen, P. (organiser) & Albert, J. (organiser) (18-11-2024). DSA Observatory Expert Workshop on Researcher access to platform data (organising a conference, workshop, ...).
    • Leerssen, P. (participant) (23-10-2024). Assessing collective Private Parties’ Litigation in the Economy of Data (participating in a conference, workshop, ...).
    • Leerssen, P. (organiser), Gorwa, R. (participant), Weigl, L. (participant) & Poell, T. (participant) (11-10-2024). Spui25: The Politics of Platform Regulation. book presentation with author Rob Gorwa and panelists Thomas Poell & Linda Weigl (organising a conference, workshop, ...).
    • Leerssen, P. (organiser) & van Hoboken, J. (organiser) (1-7-2024 - 5-7-2024). IViR Summer Course on European Platform Regulation. Organised international course for academics and professionals. (organising a conference, workshop, ...).
    • Leerssen, P. (participant) (31-5-2024). IViR Lecture Series: Kate Klonick (organising a conference, workshop, ...).
    • Leerssen, P. (participant) (16-5-2024). Delimiting Systemic Risks in Social Media Governance: Putting the DSA Into Practice. SciencesPo online workshop (participating in a conference, workshop, ...).
    • Leerssen, P. (organiser) (15-2-2024). DSA and Platform Regulation Conference 2024, Amsterdam. Organising lead for plenary programme on 16 February. (organising a conference, workshop, ...).
    • Ó Fathaigh, R. (participant), van Hoboken, J. (participant), Helberger, N. (participant), Leerssen, P. (participant) & Quintais, J. (organiser) (15-2-2024 - 16-2-2024). DSA and Platform Regulation Conference 2024, Amsterdam (organising a conference, workshop, ...). https://dsa-observatory.eu/the-dsa-and-platform-regulation-conference-2024/
    • Leerssen, P. (participant) (15-1-2024). LSE Digital Accountability Workshop (participating in a conference, workshop, ...).
    • Leerssen, P. (participant) (6-12-2023). DSA rondetafelgesprek Ministerie van Binnenlandse Zaken (participating in a conference, workshop, ...).
    • van Duin, A. (organiser), Leerssen, P. (organiser), Buri, I. (participant) & Appelman, N. (participant) (1-12-2023). Expert workshop 'Navigating the DSA's procedural turn: lessons from consumer law for ODR' (organising a conference, workshop, ...).
    • Leerssen, P. (participant) (6-7-2023). Digital Services Act Stakeholder Event: Shaping the Future of Digital Services. Moderated panel on data access (participating in a conference, workshop, ...).
    • Leerssen, P. (organiser), van Hoboken, J. (organiser) & Buri, I. (organiser) (3-7-2023 - 7-7-2023). IViR Summer Course on European Platform Regulation (organising a conference, workshop, ...).
    • Leerssen, P. (consultant) (1-6-2023 - 30-1-2024). Expert consultant on implementing regulation for researcher data access in the Digital Services Act, European Commission (DG Connect) (consultancy).
    • Leerssen, P. (participant) (23-4-2023). Mozilla Workshop on Access to Public Data, Brussels (participating in a conference, workshop, ...).
    • Ausloos, J. (organiser), Leerssen, P. (organiser) & van Drunen, M. (organiser) (15-3-2023). Researcher Access in the Digital Services Act, Amsterdam (organising a conference, workshop, ...).
    • Leerssen, P. (organiser), van Drunen, M. (organiser) & Ausloos, J. (organiser) (15-3-2023). Researcher Access in the Digital Services Act, Amsterdam (organising a conference, workshop, ...).
    • Leerssen, P. (participant) (14-2-2023). The Politics of Platformization (participating in a conference, workshop, ...).
    • Leerssen, P. (host) (1-2-2023 - 2-3-2023). Dwayne Winseck (hosting a visitor).
    • Leerssen, P. (consultant) (1-7-2022 - 31-1-2024). Expert advisor to European Commission on implementation of Article 40 DSA, European Commission (DG Connect) (consultancy).
    • Noroozian, A. (organiser) & Leerssen, P. (organiser) (22-11-2021). Roundtable on Platform Transparency, Accountability, and Auditing. Roundtable on Platform Transparency, Accountability, and Auditing (organising a conference, workshop, ...).
    • Leerssen, P. (participant) (1-6-2021). Hertie School Workshop on Detecting Digital Market Dominance (participating in a conference, workshop, ...).
    • Leerssen, P. (participant) (11-5-2021). Ada Lovelace Institute Workshop on the UK AI Strategy. Ada Lovelace Institute Workshop on the UK AI Strategy (11 May 2021) (participating in a conference, workshop, ...).
    • Leerssen, P. (participant) (14-4-2021). Organization for Security and Co-operation in Europe (OSCE) Expert Workshop on Hate Speech (participating in a conference, workshop, ...).
    • Leerssen, P. (participant) (31-3-2021). European Commission Stakeholder Workshop on transparency in sponsored political content. (participating in a conference, workshop, ...).
    • Leerssen, P. (organiser) (29-1-2021). Computers, Privacy and Data Protection Conference. Panel: Towards Research Access for Platform Data. (organising a conference, workshop, ...).
    • Leerssen, P. (participant) (29-6-2020). CEU Webinar on Free vs Protected Information (participating in a conference, workshop, ...).
    • Leerssen, P. (participant) (16-6-2020). Humboldt Institute on Workshop on Empirical Approaches in Platform Governance Research. Humboldt Institute Workshop on Empirical Approaches in Platform Governance Research (participating in a conference, workshop, ...).
    • Leerssen, P. (chair) (27-5-2020). AlgorithmWatch Governing Platforms Project Online Stakeholder Dialogue (organising a conference, workshop, ...).
    • Leerssen, P. (participant) (7-11-2019). Helsinki Committee Roundtable on privacy and political advertising. Helsinki Committee Roundtable on privacy and political advertising (participating in a conference, workshop, ...).

    2023

    • Leerssen, P. (2023). Seeing what others are seeing: Studies in the regulation of transparency for social media recommender systems. [Thesis, fully internal, Universiteit van Amsterdam]. [details]

    2020

    2022

    • Leerssen, P., Dobber, T., Helberger, N. & de Vreese, C. (2022). News from the ad archive: how journalists use the Facebook Ad Library to hold online advertising accountable. Taylor & Francis. https://doi.org/10.6084/m9.figshare.17694191.v2

    2021

    • Leerssen, P., Dobber, T., Helberger, N. & de Vreese, C. (2021). News from the ad archive: how journalists use the facebook ad library to hold online advertising accountable. Taylor & Francis. https://doi.org/10.6084/m9.figshare.17694191.v1
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