Germany’s Federal Supreme Court (BGH) has reignited a contentious legal debate by reconsidering whether browser-based ad blockers violate copyright law. The case, brought by media giant Axel Springer against Adblock Plus, centers on whether modifying website code (HTML/CSS) constitutes copyright infringement under EU Directive 2009/24/EU1. Mozilla has publicly defended ad blockers as essential privacy tools, comparing their function to skipping television commercials2.
Technical and Legal Foundations of the Case
The core technical dispute revolves around whether CSS modifications like display: none injections qualify as “computer programs” under copyright law. Axel Springer’s legal team draws parallels to the 2000 Sony v. Connectix case, where reverse engineering for interoperability was ruled fair use3. The Hamburg court will reevaluate this interpretation in 2026, with potential appeals to EU courts.
From a privacy perspective, ad blockers serve as frontline defenses against tracking scripts and malicious advertisements. Firefox’s Total Cookie Protection and extensions like uBlock Origin implement granular controls that would be compromised under a ban4. The technical community argues browsers should prioritize user agency, with one developer noting:
“The web is an arms race. Laws like GDPR are temporary fixes against ever-evolving tracking.”
Operational Impacts and Workarounds
For security professionals, ad blockers are reconnaissance tools that reveal tracking domains and prevent drive-by downloads. A ban would necessitate alternative approaches:
| Method | Effectiveness | Implementation |
|---|---|---|
| DNS-level blocking (Pi-hole/AdGuard Home) | Bypasses browser limitations but misses HTTPS-served ads | Requires network-level deployment |
| Firefox forks (LibreWolf/Floorp) | Preserves content blocking but may face legal challenges | Manual browser configuration |
| VPN + DNS combinations | Reduces tracking but impacts performance | Mullvad VPN with custom DNS |
The Manifest V3 controversy further complicates this landscape. Google’s restrictions on declarativeNetRequest rules have weakened ad blockers in Chromium-based browsers, though Firefox maintains full content blocking capabilities6.
Security Considerations and Mitigations
Organizations relying on ad blockers for threat prevention should prepare contingency plans. The Hamburg court’s 2026 decision could create jurisdictional conflicts, particularly for multinational enterprises. Recommended steps include:
- Auditing web traffic for tracking domains that ad blockers currently filter
- Testing DNS-based alternatives like Pi-hole in lab environments
- Monitoring the EU’s ePrivacy Regulation updates, which may exempt “necessary” cookies
Mozilla’s recent warning about phishing attacks targeting add-on developers underscores the stakes. Compromised ad blocker extensions could distribute malware via auto-updates to millions of users7.
Conclusion
The German legal challenge represents a pivotal moment for web privacy and security architecture. While the immediate focus is copyright law, the outcome will influence global standards for browser functionality and user control. Security teams should track both the legal proceedings and technical developments in alternative blocking methods.
References
- “Axel Springer vs. Adblock Plus: Germany’s Federal Supreme Court revives lawsuit,” BleepingComputer, 2025. [Online]. Available: https://www.bleepingcomputer.com
- “Mozilla’s stance on ad blockers as privacy tools,” Mozilla Blog, 2025. [Online]. Available: https://blog.mozilla.org
- “Sony v. Connectix fair-use precedent analysis,” Lobste.rs, 2025. [Online]. Available: https://lobste.rs
- “Firefox’s Total Cookie Protection technical documentation,” Mozilla Blog, 2025. [Online]. Available: https://blog.mozilla.org
- “User perspectives on web tracking arms race,” HN Thread, 2024. [Online]. Available: https://news.ycombinator.com
- “Manifest V3 technical limitations,” ghacks.net, 2024. [Online]. Available: https://www.ghacks.net
- “Mozilla warns of phishing attacks targeting add-on developers,” GB News, Aug. 2025. [Online]. Available: https://www.gbnews.com
