G1/23: EPO clarifies the relationship between reproducibility and prior art

In December 1992, the European Patent Office published decision G 1/92, which came to the following conclusion: “The chemical composition of a product is part of the prior art when the product as such is available to the public and can be analyzed and reproduced by the skilled person, regardless of whether particular reasons for analyzing the composition can be identified”.

Thus, the answer of G 1/92 gave rise to two distinct legal issues: it confirmed that product properties belong to the prior art, even without a specific motivation to analyze a property, but in addition, it was interpreted in certain case law as meaning that a marketed product must be reproducible in order to be considered part of the prior art. It also established that the same requirements apply to any type of disclosure: “It should also be noted that Article 54(2) EPC makes no distinction between the different means by which any information is made available to the public. Therefore, information derived from a prior use is, in principle, governed by the same conditions as information disclosed by oral or written description.”

The new decision G 1/23 clarifies that public availability, not reproducibility, is the key factor in determining whether something can be considered prior art. In essence, it defends the idea that a marketed product cannot be excluded from prior art simply because its composition is hidden. This represents a paradigm shift in the assessment of novelty and inventive step, since previous case law had interpreted decision G 1/92 in such a way as to establish the requirement that a marketed product must be reproducible to be considered part of the prior art, something that, in reality, the aforementioned decision had never specified in this way.

In the case at hand (G 1/23), the appeal was directed against the decision of the Opposition Division, which rejected the opposition against European patent EP2626911. The Division considered that the subject matter of claim 1, related to an encapsulating material for solar cells, involved an inventive step. The closest prior art was the marketed product “ENGAGE® 8400“. Certain properties of ENGAGE® 8400 were demonstrated by various technical publications. The ENGAGE® 8400 product is a complex polymer. Both parties accepted as a proven fact that the method to manufacture it exactly was not in the public domain. The exact reproduction of a complex polymer is not a simple exercise, even if the material – i.e. the final product itself – is available to the expert for analysis. The opponent argued that the expert could manufacture a product sufficiently similar to ENGAGE® 8400. The owner, that the ENGAGE® 8400 product was simply not part of the prior art because it could not be accurately reproduced.

In a part of the decision that stands out for its clarity and cogency, the Enlarged Board of Appeal notes: “the competitors of the manufacturer of ENGAGE® 8400 will take a close look at the polymer and will try to analyse it from all possible aspects. Any proposition that the product as such does not exist for the skilled person, in the sense of any skilled person – and therefore it is also irrelevant for any technical solution -, is clearly far-fetched and utterly implausible, manifestly contradicting notorious facts. So, the legally not existing but otherwise commercially available product that is even deliberately brought to the attention of skilled persons can only be regarded as a legal fiction. Legal fictions that override facts do exist in law, including patent law, but they should normally be explicitly stated in the law. These considerations alone dictate that the fiction of the exclusion of the product from the state of the art should be treated with serious reservations.”.

The Board therefore concludes that the correct interpretation of decision G 1/92 is that the chemical composition of a product is part of the prior art when the product as such is available to the public and can be analyzed by the skilled person, whether or not particular reasons for analyzing the composition can be identified. That is, it does not include the requirement that the composition has to be reproducible. This is a decision to be taken into account in the case of patent oppositions when the prior art includes products that are commercially available on the market, because even if the exact “recipe” of the product is unknown and irreproducible, it is considered prior art. The evaluation of the novelty or inventive step of other products in view of those already in circulation must be made, however, on a case-by-case basis.