December 2025 The EPO Technical Boards of Appeal (TBA) decision in T 1044/23 offers the first practical insight into how the EPO Enlarged Board of Appeal (EBA) decision in G 1/23 will shape novelty and inventive step assessments when the prior art consists of commercially available products whose manufacturing processes remain undisclosed, i.e. effectively an intellectual “black box.”
Background
Under G 1/92, a product on the market was not considered “available” as prior art under Article 54(2) EPC if the skilled person could not reproduce it without undue burden. This created a peculiar legal fiction: a product could be purchased yet legally ignored in patentability assessments if it was unknown how to reproduce it.
G 1/23 addressed this legal fiction and the Enlarged Board confirmed that a product cannot be excluded from the state of the art solely because its composition or internal structure could not be analysed and reproduced before the filing date. Thus, commercial availability can prejudice novelty, even if the means of producing the commercial product remains secret.
The Patent: Polyethylene Compositions and DMDA Resins
The patent at issue (EP 3 161 066 B1) claims a polyethylene composition for injection moulding. The Opponent argued that sale of resins DMDA-8904 NT 7 and DMDA-8907 NT 7 disclosed the claimed invention or rendered it obvious, i.e. lacking inventive step.
Resins DMDA-8904 NT 7 and DMDA-8907 NT 7 were widely used but the details enabling their manufacture, in particular the choice of catalyst and reaction conditions needed, were not publicly disclosed. The question was thus whether such “black box” products still count as prior art, particularly in respect of inventive step.
Turning to novelty and applying decision G 1/23, the TBA confirmed that lack of reproducibility does not prevent the product being publicly available and therefore applicable to novelty. The opponent’s evidence comprised sales invoices and certificates of analysis in order to demonstrate public availability. Notwithstanding this analysis, the facts of the case resulted in an acknowledgement that the claims in question were novel.
Inventive Step: Can You Adapt What You Cannot Make?
The patentee argued that because the DMDA resins could not be reproduced, they were unsuitable as a starting point for the EPO’s preferred “problem-and-solution” approach for analysing inventive step. The TBA disagreed.
Again referring to G 1/23, the TBA noted that even a non-reproducible product may serve as the closest prior art. For example, if the product is publicly available, a skilled person can still use the product as-is or attempt to modify it. The TBA noted that “this situation essentially corresponds to the example in G 0001/23, according to which: “Adding some lemon juice to a glass of Coca-Cola for a less sweet taste may not be inventive simply because the recipe for Coca-Cola is secret and therefore the original taste of Coca-Cola is considered as unattainable.” (T 1044/23, r. 5.1.8; G1/23 r. 96).
Further, the TBA distinguished tangible commercial products from “speculative disclosures,” confirming that the former remain valid starting points for inventive step analysis, “whereas the latter are non-concrete disclosures lacking the necessary technical reality” (T 1044/23, r.5.1.9).
Again, despite the availability of resins DMDA-8904 NT 7 and DMDA-8907 NT 7 as prior art, the TBA was able to confirm the presence of an inventive step.
Conclusion
Accordingly, claims were found to be novel and inventive, and therefore the patent was remitted to the opposition division with the order to maintain it [based on Auxiliary Request II].
Thus, looking at the practical implications of Decision T 1044/23 we observe that:
• Prior use attacks on novelty are strengthened.
Opponents can now rely on commercially available products even if the manufacturing process of that product is secret.
• Patentees must take account of “black-box” prior art disclosures.
Thus when drafting claims it should be taken into account that trade-secret products may still prejudice the novelty and inventive step of the claims.
• Interplay between patent rights and trade secrets
T 1044/23 highlights the growing importance of coordinating the protection yielded by patent rights and that yielded by trade secrets. This is because of the commercial value of a trade secret and because trade-secret products may undermine competing patent rights.
EPO TBA Decision T1044/23 can be read here.
