German Federal Court refers ad blocker case back to Hamburg Higher Regional Court

On 31 July 2025, the German Federal Court of Justice (Bundesgerichtshof, BGH) issued its decision (decision of 31 July 2025 - I ZR 131/23) in the long-running dispute between Axel Springer and Eyeo (Adblock Plus), referring the case back to the Higher Regional Court of Hamburg for further examination. (Our previous blog, Germany: Copyright and ad blockers, summarises the earlier stages of this litigation.)

At the heart of the case is the copyright status of browser-generated data structures - specifically DOM and CSSOM trees - in the context of ad blocking technologies.

Springer had argued that the programming of its websites, including control elements, qualifies as a computer program under section 69a(1) of the German Copyright Act (UrhG).

The BGH:

• Considered it plausible that client-side processes, such as the interpretation of bytecode by browser engines, could be protected under copyright law.
• Noted that the use of ad blockers might constitute an adaptation or modified reproduction under section 69c UrhG, but found that the lower court had not made sufficient factual findings to support such a conclusion.

The judgment does not provide a final assessment of whether the functionality of Adblock Plus constitutes an adaptation within the meaning of section 69c UrhG. Instead, it highlights the technical complexity of browser processes and the need for a nuanced legal analysis.

Although the CJEU’s October 2024 ruling in C-159/23 (Cheat Software) (see our earlier blog, German Federal Court of Justice decision in Sony v. Datel: Its implications for gaming, cheat tools and EU software copyright law) is not explicitly referenced, its underlying reasoning may still be indirectly relevant. In that case, the CJEU clarified that temporary, user-side modifications to data structures do not automatically amount to copyright infringement.

Final observations

The BGH’s decision is likely to shape ongoing debates around digital advertising, user rights and the copyright protection of dynamically generated structures.

It also underscores the limitations of traditional software protection frameworks - particularly in relation to runtime processes such as browser rendering.