{"id":2421,"date":"2025-07-25T16:34:06","date_gmt":"2025-07-25T14:34:06","guid":{"rendered":"https:\/\/blog.eprivacy.eu\/?p=2421"},"modified":"2025-07-25T16:34:07","modified_gmt":"2025-07-25T14:34:07","slug":"data-clean-rooms-privacy-enhancing-collaboration-instead-of-data-deserts","status":"publish","type":"post","link":"https:\/\/blog.eprivacy.eu\/?p=2421","title":{"rendered":"Data Clean Rooms \u2013 Privacy-Enhancing Collaboration Instead of Data Deserts?"},"content":{"rendered":"\n

The demand for more data remains unbroken\u2014in marketing, finance, as well as in research. At the same time, businesses and institutions face regulatory pressure to protect personal data in compliance with the GDPR. In this context, Data Clean Rooms (DCRs) are gaining momentum as a technical and legal infrastructure for secure collaboration between data-processing entities.

What is a Data Clean Room from a Privacy Perspective?<\/strong>

A Data Clean Room allows multiple parties to combine their datasets in a shielded analytics environment\u2014without raw data leaving the parties‘ own infrastructure or becoming visible to other participants. Data is often shared in hashed, aggregated, or pseudonymized form. The economic appeal is clear: businesses can monetize their data, gain insights even through cooperationwith competitors, or optimise their business processes\u2014without disclosing trade secrets or risking re-identification.

Data Protection as an Enabler \u2013 Not a Showstopper<\/strong>

From a legal perspective, the key question is the following: does the operator of the Data Clean Room have access to any personal data? If the system is designed in such a way that a re-identification of the data subjects behind the data sets is technically impossible for the DCR operator, the transmitted data could be considered anonymised. In this case, the GDPR would not fully apply\u2014particularly regarding transparency obligations, legal basis requirements, or retention periods.

This very issue is currently being reviewed by the European Court of Justice (ECJ): in the so-called SRB case, the court is assessing the definition of \u201cpersonal data\u201d in relation to pseudonymised information. Should the ECJ endorse the so-called relative identifiability test\u2014that is, whether a specific data recipient can identify a data subject\u2014this would have far-reaching implications. It would pave the way for simplified and GDPR-compliant application of many Data Clean Room models.

Currently, six use cases are emerging where Data Clean Rooms can provide added value: <\/p>\n\n\n\n

  1. Campaign and Attribution Measurement<\/strong>
    CRM-derived hash IDs can be matched with publisher data\u2014without either party accessing raw data. Particularly relevant as third-party cookies are phased out.<\/li>
  2. Second-party data enrichment<\/strong>
    Two businesses combine customer lists to analyze shared audiences\u2014without exposing master data. A win for both privacy and antitrust compliance.<\/li>
  3. Product and market research<\/strong>
    Loyalty data, panel responses, and social listening data are analysed under differential privacy constraints\u2014ensuring that individual statements remain statistically untraceable.<\/li>
  4. Fraud and risk scoring<\/strong>
    Banks can exchange suspicious transaction patterns; the DCR calculates risk scores. This is especially useful in highly regulated industries, supported by Secure Multi-Party Computation (SMPC).<\/li>
  5. Group-wide 360\u00b0 analytics<\/strong>
    Subsidiaries share pseudonymized IDs; the holding company receives consolidated KPIs. From a privacy perspective, this is often permissible on the basis of legitimate interests (art. 6(1)(f) GDPR).<\/li>
  6. Federated learning for AI modell<\/strong>
    An AI model can be trained where the data resides. Only gradients are transmitted to a central location\u2014an innovative approach to privacy-friendly AI development <\/li><\/ol>\n\n\n\n

    Key Governance requirements for compliant technology use<\/strong>

    For a Data Clean Room to be effective both technically and in a legal sense, clear role definitions and binding contractual frameworks are essential. The European Data Protection Board\u2019s Guidelines 07\/2020 offer crucial guidance on distinguishing between joint controllership and processor relationships for this purpose.

    Equally important are robust technical safeguards, such as: <\/p>\n\n\n\n