A blog series by Zoltán Gyenge and Thomas Wyder
(Software Practice Group at Rentsch Partner)

In Part I, we explored how the Enlarged Board of Appeal’s landmark decision G 1/23 refined the “disclosure test” under the EPC, recognizing de facto disclosure, associated with factual availability, as prior art while maintaining the higher standard of enabling disclosure for patentability.

Let us assume a consumer electronics product (e.g., a smart speaker or router) is commercially available before the filing date (effective date) of a patent application. The product contains embedded firmware stored in read-only memory and which has various functions. The firmware is deployed in compiled form only and its logic is not publicly documented.

While extracting and analyzing the firmware would theoretically be possible and the device’s external behavior (e.g., response to commands, communication protocols) is observable by users, the internal software logic of the device cannot be reproduced.

The Disclosure Double Standard of G 1/23

The above-sketched scenario concerning the consumer product with embedded firmware allows bringing the disclosure double standard emerging from G 1/23 into sharp focus:

1. No Requirement of Reproducibility for a Product to Constitute Prior Art
   
   

   Applying G 1/23, a publicly available device as such constitutes prior art including the firmware’s observable functions, as in G1/23, the Enlarged Board clarified that a product’s composition or internal structure need not be reproducible for the product to form part of the state of the art under Article 54(2) EPC.

   In the sketched scenario, the device is publicly available and any observable functionality of the firmware, such as its outputs, UI behavior, or network interactions, qualify as technical information made available to the public. The internal mechanisms may remain opaque, but the device itself is a de facto disclosure. In other words there is no legal fiction of its inexistence as prior art due to lack of reproducibility.

   G 1/23 makes it clear that what matters is factual availability, not whether the product can be reverse engineered to a degree which would enable reproducibility. Therefore, any objectively discernible behaviors (even if derived indirectly from use or testing) become part of the state of the art, regardless of whether the internal software logic can be reproduced.
   
   

2. Enablement Requirement for Patentability
   
   In contrast, if an applicant tries to patent the same internal software logic as implemented in the firmware, the European patent application must meet the enablement requirement under Article 83 EPC. The claimed invention would need to be disclosed in a manner sufficiently clear and complete for the skilled person to put it into practice, that is, to reproduce the functionality without undue burden or inventive effort.
   
   In practice, this means that patent protection of embedded firmware prerequi-sites disclosure of the internal software logic, of the technical implementation, sufficient to enable a skilled person to reproduce the claimed subject-matter.

Implications for Practitioners

Patent professionals must recognize that functionality deployed in the firmware of publicly available products counts as prior art, even if it is not reproducible by a person skilled in the art. Observable functionality becomes part of the public domain upon release of the product. Therefore:

• Patent claims to functionality of firmware must be carefully assessed against the behavioral footprint of publicly available products, respectively their own potentially hidden firmware.
• Enablement remains a hard requirement: even if the claimed functionality is known from prior art products, an enforceable patent claim must be backed up by enabling disclosure of a reproducible implementation.

In conclusion, it appears that following the Enlarged Board’s decision in G 1/23, a publicly available product, effectively associated with the disclosure of features at a level of detail which, if included analogously in a patent application, would be considered a result to be achieved will prevent the patenting of a technical implementation of the same feature later on.

Shifting the Balance in the Contract Theory of Patents

One of the basic theories behind the patent system is the so-called “the contract theory of patents”: the state grants a time-limited monopoly in exchange for disclosure. The terms of the (fictitious) “contract” which a patent represents, are: Teach the public how your invention works, and in return, enjoy a period of exclusivity. Upon expiry of the period of exclusivity, the public is free to use your work. Moreover, the public can immediately learn from your (enabling) disclosure.

The time-limited monopoly as a reward for disclosure is intended specifically to disincentivize reliance on trade secrets as the primary means of protecting technological innovation. By requiring an enabling disclosure, the patent system fosters society’s cumulative progress of technology and promotes that technical knowledge enters the public domain.

The balance in the contract theory of patents appears to be maintained when either dealing with:

• Black boxes: Products that are not analyzable at all using common general knowledge. These do not constitute prior art and do not block anyone from patenting later on. They remain legitimate targets for subsequent patent applications comprising enabling disclosures.
• “Transparent” boxes: Products whose inner workings are fully analyzable and reproducible. They block anyone from patenting later on, but they do so by providing the public with a technical teaching, fostering society’s cumulative progress of technology.

However, G 1/23, when applied to grey box products that are publicly available and partially analyzable, but not reproducible, opens up a troubling possibility:

A company may now release a product on the market with firmware implementing novel functionalities, keep the technical teaching secret, but is nevertheless still able to limit others in patenting the same invention. Thus, the balance in the contract theory appears to have shifted against the public interest.

This is not mere theory. It is particularly relevant for embedded firmware and software-driven devices, where:

• The product's behavior is externally observable, making certain technical features analyzable;
• The internal software logic remains hidden, e.g., in compiled form;

Conclusion

The application of G 1/23 to products comprising embedded firmware reveals a significant revision to how prior art is assessed under the European Patent Convention. The decision holds that factual availability (i.e., de facto disclosure), not reproducibility (enabling disclosure), determines whether a product forms part of the state of the art. Consequently, products with embedded firmware, whose behavior is externally observable but whose internal logic remains unreproducible (coined “grey boxes” in this blog), can prevent later patenting by anyone despite the fact that there was no reveal of any reproducible technical teaching to the public.

This development invites reflection on the so-called contract theory of patents, whereby exclusive rights are granted in exchange for the disclosure of inventions to the public. When grey boxes are put on the market, the possibilities of patenting such products is limited for the future and, hence, the incentive for patenting and disclosing an invention to the public is reduced, without the public being privy to a new technical teaching. Thus, one may be tempted to conclude that step-by-step disclosure of chunks without achieving overall enabling disclosure allows eating away at the public interest. In summary, the question is raised whether the traditional balance between disclosure incentive through state-granted monopoly and public benefit still holds in technology domains where reproducibility cannot be readily achieved from what is publicly analyzable.