Lawsuit Filed Against Microsoft for Alleged Unlawful Data Processing for Advertising

Microsoft Ireland Operations is facing a lawsuit in the first High Court representative action under new legislation for allegedly processing personal data unlawfully, earning billions in advertising revenue.

The Irish Council for Civil Liberties (ICCL) claims that Microsoft operates an advertising business through its Xandr platform, selling advertising slots to individual advertisers in a real-time bidding system for a fee.

It is alleged that Microsoft's 'search and news advertising' business made around $10.2bn (€8.6bn) in the nine months ending March 2025.

The ICCL is seeking declarations and orders against Microsoft Ireland Operations Ltd to stop such data processing or adjust it to comply with GDPR and Irish law.

In May, the High Court approved the ICCL's action as a representative action under the 2023 Protection of the Collective Interests of Consumers Act, the first case under this act.

On Monday, the case was admitted to the fast-track Commercial Court list. Microsoft's counsel did not object but raised concerns about the defendant being Xandr instead of Microsoft.

Justice Eileen Roberts adjourned the case for three weeks to allow parties to exchange correspondence regarding funding and the correct defendant.

Johnny Ryan, a senior fellow with the ICCL, stated that Microsoft's revenue figures were disclosed in the company's submission to the US Securities and Exchange Commission, but the ICCL's concerns were not satisfied by Microsoft's documents.

Mr. Ryan believes that delaying the proceedings and the rights of Irish consumers is the motive behind claiming Microsoft is not the correct defendant.