The Federal Circuit recently declined to reconsider its decision invalidating Merck KGaA’s patents covering the blockbuster MS drug Mavenclad.
While the headlines focus on the drug, the deeper lesson for IP professionals lies in the court’s strict treatment of “prior art by another.”
The Core Holding (Pre-AIA Law)
Merck argued that an earlier disclosure should not count as prior art because it came from its own scientists. The problem was inventorship mismatch.
Because the inventors on the earlier disclosure did not exactly match the inventors on the later patent, the court applied a bright-line pre-AIA rule:
If the inventive entities are not identical, the reference is “by another” and may support an obviousness challenge.
Partial overlap was not enough.
Important Scope Note
This ruling arises under pre-AIA law, which still governs many valuable pharmaceutical and biotech portfolios. The same bright-line rule does not apply wholesale to post-AIA patents—but the cautionary lesson remains highly relevant.
Why This Still Matters
Long-term life-sciences R&D rarely involves static teams. Scientists rotate, collaborations expand, and early findings are often published years before final claims take shape. Under pre-AIA rules, those early disclosures can quietly mature into fatal prior art.
Sometimes, the most dangerous reference is your own earlier work.
Three Key Takeaways for IP Teams
🔹 Inventor Identity Was Absolute (Pre-AIA)
A subset of inventors is not equivalent to the full inventive entity.
🔹 Inventorship Must Be Tracked Early and Continuously
Post-hoc corrections are often too late.
🔹 Collaboration Creates Latent Risk
Internal publications and joint research can unintentionally undermine later filings if not carefully managed.
The Mavenclad decision is a reminder that in patent law, innovation without coordination can be self-defeating.
Appellate Case No.25-1210, 25-1211
