On 14 May 2025, the Belgian Market Court (part of the Brussels Court of Appeal) delivered a landmark judgment in the case concerning IAB Europe’s Transparency and Consent Framework (TCF).

The case centred on allegations that IAB Europe violated the General Data Protection Regulation (GDPR, or AVG in Dutch) through its data processing practices within the TCF. This judgment follows an earlier decision by the Belgian Data Protection Authority (APD), which found several breaches of the GDPR and imposed a €250,000 fine on IAB Europe.

CASE BACKGROUND

IAB Europe is an international non-profit association aiming to bring compliance to the digital advertising and marketing sector. They developed the TCF to promote adherence to the GDPR when internet sites or applications use the OpenRTB protocol.

On 2 February 2022, the APD found that IAB Europe’s TCF violated GDPR and fined IAB €250,000. Key findings included:

• The TC String (user preferences signal) is personal data.
• IAB Europe is a joint controller for both the creation and subsequent processing of the TC String.
• Lack of a valid legal basis for processing TC Strings as the TCF did not obtain explicit and informed consent from users, nor could it rely on legitimate interests due to the large-scale and intrusive nature of the data processing involved.
• Failure to fulfil transparency obligations and not adequately informing users about its role as a data controller, the purposes of data processing, or the recipients of their data.
• Inadequate security measures and lack of mechanisms to prevent manipulation of consent signals.
• Failure to conduct data protection impact assessments.
• Failure to appoint a data protection officer. 
• Incomplete register of processing activities.

On 4 March 2022, IAB Europe challenged the APD’s decision before the Belgian Market Court, disputing its role as a joint controller and the APD’s legal analysis on the TC String being personal data.

On 7 September 2022, the Belgian Market Court made an interim ruling, confirming the procedural irregularities in the APD’s investigation. It referred two preliminary questions to the CJEU:

• Does the TC String constitute personal data under GDPR?
• Is IAB Europe a joint controller for processing TC Strings and subsequent data uses?

On 7 March 2024, the CJEU judgement confirmed that:

• the TC String may constitute personal data if:
  1. It is associated with other data points (e.g., IP address) that can identify a user.
  2. IAB Europe has reasonable means to access such data.

• IAB Europe may be a joint controller for the creation and use of TC Strings if it influences the processing’s purposes and means.
• IAB Europe is not a joint controller for subsequent processing (e.g. personalised advertising) by third parties.

The case was sent back to the Belgian Market Court for factual verification and further examination which this article explains.

FINDINGS OF THE MARKET COURT

Are TC Strings Personal Data?

TC Strings are unique codes containing users’ consent preferences.

The Market Court referenced the preliminary ruling of the CJEU in March 2024, which clarified that TC Strings, when linked to identifiers such as IP addresses, allow for user identification.

In paragraph 48 of the judgment, the Market Court stated that “the fact that IAB Europe itself would not have the reasonable means to proceed with Identification because it cannot make the link between a TC String and the IP address and would not have direct access to the personal data, is in itself irrelevant”.

As such, the Market Court confirmed that a TC String is personal data within the meaning of Article 4(1) of the GDPR.

Is there any processing of personal data?

IAB Europe, as the managing organisation and central figure in the digital ecosystem, determines the storage and dissemination of the TC String.

Under the TCF Technical Specifications, the TC String is shared with Consent Management Platforms (CMPs) in two ways:

• By storing it in a shared global consent cookie on IAB Europe’s consensu.org domain; or
• By storing it in a CMP-chosen system for service-specific consent signals.

The Market Court found that storing the TC String in a shared cookie and making it available via the consensu.org domain clearly constitutes processing of personal data under GDPR.

The Market Court further explained that, regardless of the consent cookie or domain, processing of personal data occurs in the TCF, including:

• User preferences being collected by CMPs (along with the user’s IP address);
• User preferences being structured and ordered in a TC String; and
• The TC String being stored, distributed, and shared with TCF participants.

Should IAB Europe’s Role in the TCF be considered as a Data Controller?

Paragraphs 62-75 of the judgment confirms that it is clear that IAB Europe has real decision-making power, both over the purposes and means of processing and this given its overriding control over the operation of the TCF:

• IAB Europe acknowledges its responsibility for the TCF in its own documentation – such as “Frequently Asked Questions” on the TCF (version 2.0) – noting that this judgment only focusses on v2.0 as IAB Europe’s TCF v2.2 already includes updates to address compliance concerns raised.

• On determining the purpose and means of these processing operations, IAB Europe indeed exercises a decisive influence. IAB Europe has a shared purpose with the other participants for the processing of personal data, which incidentally all have the same, which is to ensure that user preferences are captured in a structured way and then shared with all other participants. Even though many TCF participants may be competitors, when it comes to the processing of user preferences under the TCF, they all have similar interests, which are also similar to those of IAB.

The Market Court states that “the concept of a data controller in this case just does have to interpreted broadly, since IAB Europe is the only one who, as it itself states, manages and administers the TCF and can therefore resolve the issues identified by the Dispute Resolution Chamber, after consultation with all other EU regulators.”

The Market Court confirmed that IAB Europe is a joint data controller with TCF participants for storing the consent preferences of the affected users in the TC String.

If yes, is IAB Europe a Joint Controller for the processing of personal data in the context of OpenRTB?

The Market Court assessed whether IAB Europe with the TCF “influences” the further processing of personal data under OpenRTB.

The APD argued that IAB Europe’s TCF and OpenRTB are inherently interconnected. It claimed that IAB Europe facilitates an ecosystem where consent preferences are collected and shared for further processing by third parties (e.g. publishers and adtech vendors). As such, the ADP considered IAB Europe and participating organisations to be joint controllers for both the collection and dissemination of consent data.

The Market Court identified inconsistencies in the ADP’s reasoning. Although the ADP acknowledged that IAB Europe does not act as a data controller for processing under OpenRTB, it nevertheless implied such responsibility in its decision. The Market Court found that the Appellants had limited the scope of their arguments to the TCF, no evidence was provided to establish IAB Europe as a joint controller for OpenRTB processing and it lacked influence over this stage of data use..

It concluded that the APD failed to demonstrate that IAB Europe acts as a joint data controller for processing operations under OpenRTB as not all processing stages fall under their control.

OUTCOME

The Market Court upheld the €250,000 fine imposed by the APD, deeming it proportionate and justified under Article 83 of the GDPR. It also confirmed the corrective measures requiring IAB Europe to bring its processing activities into compliance.

The Market Court dismissed most of IAB Europe’s grievances but acknowledged procedural flaws in the initial decision. It upheld the APD’s sanctions regarding TCF operations but clarified that IAB Europe is not responsible for OpenRTB operations – annulling the APD’s decision in part.

IAB Europe is ordered to pay the costs of proceedings, estimated at €7,848.84, and other contributions totalling €424.

IMPLICATIONS

This Judgment clarifies that even entities without direct access to personal data can be held accountable as data controllers if they influence the purposes and means of processing.

For the adtech industry, this ruling reinforces the GDPR principles and in particular supports the requirements to:

• carefully examine consent mechanisms to ensure they are transparent, freely given, specific, informed and unambiguous;
• ensure the use of consent frameworks like the TCF does not create ambiguity about their own roles and accountability in data processing operations;
• provide users with clear, accessible, and understandable information about how their data is processed; and
• minimise the processing of personal data by leveraging contextual advertising, privacy-enhancing technologies, and aggregated or pseudonymised datasets instead of third party cookies.

AUTHORS