G1/23: If it is public, it is prior art

A product made publicly available before a patent's filing date cannot be excluded from prior art simply because its composition or structure could not be fully analysed or reproduced. The Enlarged Board of Appeal made this decision in a dispute between Mitsui Chemicals and Borealis.

In its groundbreaking decision G1/23, the Enlarged Board stated that any technical information about a product that is publicly accessible is part of the state of the art, regardless of whether a skilled person could replicate it. This follows the recent high-profile decision in G1/24 on assessing patentability.

The decision stems from a dispute between patent owner Mitsui Chemicals and opponent Borealis over EP 2 626 911, which protects solar cell sealing material and a solar cell module.

Opposition dismissed

In September 2016 Borealis filed an opposition against the patent granted in November 2015. The company, which provides solutions in polyolefins, argued that a polymer marketed as Engage 8400 was commercially available and part of the prior art before the patent’s effective date.

However, as Engage 8400 is a complex polymer, both parties agreed that its manufacturing method was not in the public domain. They also agreed that exact reproduction of a complex polymer is not straightforward, even if the material is available for analysis. Borealis argued only that a skilled person could make a product sufficiently similar to Engage 8400. The parties disagreed on whether the product belonged to the state of the art for inventive step purposes.

In December 2018, the EPO rejected the opposition. The Opposition Division found that claim 1’s subject matter, relating to solar cell encapsulating material, involved an inventive step. Borealis appealed this decision.

Questions referred

In June 2023, Technical Board of Appeal 3.3.03 referred the following questions to the Enlarged Board of Appeal (case ID: T 0438/19):

Is a product put on the market before the date of filing of a European patent application to be excluded from the state of the art within the meaning of Article 54(2) EPC for the sole reason that its composition or internal structure could not be analysed and reproduced without undue burden by the skilled person before that date?

If the answer to question 1 is no, is technical information about said product which was made available to the public before the filing date (e.g. by publication of technical brochure, non-patent or patent literature) state of the art within the meaning of Article 54(2) EPC, irrespective of whether the composition or internal structure of the product could be analysed and reproduced without undue burden by the skilled person before that date?

If the answer to question 1 is yes or the answer to question 2 is no, which criteria are to be applied in order to determine whether or not the composition or internal structure of the product could be analysed and reproduced without undue burden within the meaning of opinion G 1/92? In particular, is it required that the – 3 – G 0001/23 composition and internal structure of the product be fully analysable and identically reproducible?

Findings

The Enlarged Board ruled that a product on the market before a European patent application’s filing date cannot be excluded from prior art solely because its composition or internal structure could not be analysed and reproduced. Technical information available to the public before the filing date forms part of the state of the art regardless of whether the skilled person could analyse and reproduce the product.

The EBA noted that disclosed but non-reproducible features may affect inventive step assessment. It clarified: “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. On the other hand, achieving the original taste of Coca-Cola without sugar or caffeine is probably an unsolved problem at the time of writing.”