If you’ve ever wondered how online ads seem to follow you around the internet, you’re not alone. Behind the scenes, a process called real-time bidding (RTB) is likely at work. It’s fast, clever, controversial, and now at the centre of a major legal battle – the Microsoft data breach claim brought by the Irish Council for Civil Liberties (ICCL).
Here’s how it works, and why it could affect users across the UK.
What is real-time bidding?
RTB is the engine of today’s online advertising world. When you visit a website, your personal data is shared with hundreds of potential advertisers in real time, before the page even finishes loading.
These companies bid for the chance to show you an ad based on:
- Your location and IP address
- Your browsing history
- The device you’re using
- Your inferred interests and demographics
It happens in milliseconds, and it’s largely invisible to the average user.
Why is it a problem?
The ICCL alleges that Microsoft’s real-time bidding system is sharing far more personal and sensitive information than it should, and doing so without proper consent.
This could include data such as:
- Your political views
- Religious beliefs
- Sexual orientation
- Financial difficulties
- Health conditions
- Online habits and app use
- Information about children or family members
If true, this would be a clear breach of GDPR and a serious violation of user privacy.
The Microsoft data breach claim
The ICCL’s case, filed in Ireland in May 2025, is the first class-style consumer privacy action under the country’s new Representative Actions Act. It’s designed to protect consumers when mass violations happen, especially when individual complaints wouldn’t carry enough weight on their own.
While the action is currently focused on injunctive relief (i.e. stopping the behaviour), it could pave the way for consumer compensation claims in the UK, if similar breaches are found here.
Why this matters for UK users
If the court finds that Microsoft broke the rules, it could open the door to compensation claims across the EU – including here in the UK. That’s where we come in. If a UK claim is launched, we’ll help you check if you qualify and connect you with a trusted law firm.
Most people never consent to their data being shared with dozens (sometimes hundreds) of third parties. This case could be a game-changer in how the ad industry operates, and how your rights are protected.
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Register your interest and we’ll keep you in the loop if a UK Microsoft data claim is launched.
