The German Federal Patent Court (BPatG) recently ruled that a 100-year-old patent can still kill a modern utility model (Case 35 W (pat) 411/23). But here is the catch: this happened because the field of sewage sludge drying is considered a “slow-mover” with very long development cycles.
What if your industry moves at lightning speed?
If this case had occurred in a field with continuous, rapid development cycles (like AI, biotech, or semiconductors), the outcome might have been completely different. Here is how the legal logic shifts when the “technical environment” is constantly evolving:
The “Visibility” Factor: Out of Sight, Out of Mind?
The court emphasized that a “skilled person” (Fachmann) only looks at historical documents if they are still “recognizable in the environment of modern teaching”.
- In stagnant fields: Basic concepts (like scrapers on drying surfaces) remain relevant for decades, making 1921 prior art a “fair game” starting point.
- In fast-paced fields: A 100-year-old solution is often considered technically obsolete. If a field undergoes constant disruption, an expert is far less likely to consult a manual from the 1920s because the underlying physics, materials, or software logic have fundamentally shifted.
Critical Reflection:
The “Rediscovery” Argument – The court’s primary goal is to prevent the “mere rediscovery of known technical concepts”. However, in a fast-moving industry, “rediscovering” an old concept and making it work with modern, high-speed technology often requires a genuine inventive step rather than just a modular update. The “temporal distance” then becomes a strong indicator for inventiveness, not against it.
Revised Practice Tips for Dynamic Industries
- Argue “Technical Discontinuity”: If challenged by old prior art, demonstrate that your industry has moved past the “old” logic. Prove that the historical solution was forgotten because it was superseded by better technology, making its re-adoption non-obvious.
- The “Search Horizon” Defense: Argue that a modern developer in your specific field would not include a century-old patent in their “standard search horizon” because the technical requirements (speed, precision, scale) have changed so drastically.
- Highlight Integration Complexity: In fast-moving fields, the “modular combination” of old ideas with new formats is often technically difficult. Focus your patent strategy on the unique interfaces and adjustments needed to make the old concept survive in a modern environment.
- Monitor the “State of Stagnation”: Be aware of which parts of your tech are “traditional” and which are “high-tech.” Even in a fast industry, “low-tech” components (like simple mechanical frames) might still be vulnerable to very old prior art.
The Bottom Line: Age is just a number—unless your industry hasn’t changed since your great-grandfather was in school. The more dynamic your field, the stronger your defense against the “ghosts” of patents past.