Stretching the cheese: Contradictory evidence for a purported technical effect relied on for inventive step (T 0629/22)

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T 0629/22 considered how the credibility/plausibility of a claimed invention should be addressed in the face of contradictory evidence for the technical effect relied on for inventive step. The evidence requirement for inventive step was recently considered by the Enlarged Board of Appeal (EBA) in G 2/21. Neither G 2/21 nor the subsequent decision by the referring Board of Appeal directly considered the question of contradictory evidence from opposing parties. The decision in T 0629/22 provides some guidance on how this issue should be approached.  

Credibility of a product claim

The case in T 0629/22 related to vegan cheese (EP3422865). Claim 1 of the main request on appeal specified “a cheese analogue, comprising water, 10-24 wt.% of a non-modified root or tuber starch or of a waxy root or tuber starch comprising at least 90 wt.% amylopectin, 0.5-8 wt.% native potato protein and a fat component”. The main attack from the Opponent was that the claims lacked inventive step. 

Cheese testing

The prior art described a vegan cream cheese that also contained potato starch, potato protein and fat, and was made using a similar manufacturing process. The patentee argued that the claim was distinguished from the prior art vegan cheese with regards to the type and amount of starch used. The patentee argued that the “non-modified root or tuber starch or of a waxy root or tuber starch” of the claimed cheese made the cheese stretchy when melted (i.e. like mozzarella). However, the Board of Appeal noted that the examples provided in the patent, showing the superior “melt-stretch characteristics” of various cheeses, all related to cheeses manufactured in a particular way. The cheeses were all made, for example, by heating to induce gelatinisation of the starch, where starch gelatinisation is essential for achieving the required melt-stretch characteristics of the cheese

By contrast, the claim did not include any features specifying the manufacturing process of the claimed cheese. For the Board of Appeal, the question thus arose whether cheeses made in a different way would still have the technical effect relied on for inventive step. In other words, was it “credible that any product as defined in claim 1 has those characteristics, irrespective of its manufacturing method”? The question was thus a classic one of whether the claimed product plausibly/credibly had the technical effect relied on for inventive step (IPKat). 

In answer to this question, the Board of Appeal found that the patent itself specified that a heating step was required for starch gelatinisation and achievement of melt-stretch cheese. As such, the Board of Appeal concluded that “it is not credible that cheese analogues which are prepared using the relevant ingredients but are not subjected to the manufacturing steps described in the examples of the patent, and in particular to the heating step, will have the purported melt-stretch characteristics” (r. 2.14). 

The question then became whether the different types and amounts of starch specified in the claims would have been obvious to a skilled person trying to make an alternative type of cheese lacking any particular technical effect. The Board of Appeal found that the types and amounts of starch would have been obvious alternatives, and thus that the product claim lacked inventive step. 

Credibility of a product-by-process claim

The Board of Appeal then went on to assess the inventive step of a product-by-process claim for the cheese in which the manufacturing steps were specified. The claim had the same distinguishing feature from the prior art as the product claim, namely the type and amount of starch used in the cheese. The claim also included the heating step missing from the product claim. The patentee argued that the inclusion of the heating step meant that all cheeses falling under the scope of the claim would have the purported technical effect of good melt-string characteristics. The opponent submitted that this was not the case. 

The opponent submitted the results of experiments showing that cheeses prepared according to the specified method did not have the required levels of melt-stringiness. However, these results were then contradicted by results from the patentee’s tests of the same cheese. In the patentee’s hands, the same cheeses were melt-stringy. The Board of Appeal was convinced that the difference in the results could be put down to a difference in experiment set-up, and the use of different tests of stretch. The opponent used a fork to test stretch, whereas the patentee used a spatula, and forks led to a lower measure of stretch. In view of this explanation, the Board of Appeal was satisfied that the technical effect relied on by the patentee was credible, even in the face of contradictory data from the opponent. 

The opponent also submitted evidence that the technical effect was not achieved for certain embodiments of the claimed invention using particular types of starch and amounts of the other components. As such, the opponent argued, the technical effect was not achieved over the whole scope of the claim. The Board of Appeal was not convinced by this argument, and found that that the skilled person would be able to use the teaching provided in the application as filed to make appropriately stretchy cheese. The Board of Appeal thus concluded that the presence of a single non-working embodiment was of no harm (r. 6.19), and the claims were found inventive. 

How to approach contradictory evidence following G2/21

G 2/21 confirmed that post-published evidence may be used to support a technical effect relied on for inventive step (IPKat). In G 2/21 related to a scenario in which the patentee and opponent both submitted data, purporting to support or undermine, respectively, the technical effect relied on for inventive step. However, in applying G 2/21, the referring Board of Appeal in the case, did not tackle the question of what should be done in the scenario of conflicting post-published evidence (T 0116/18). The contradictory evidence submitted by the opponent with regards to the technical effect eventually relied on by the patentee was filed after G 2/21 was issued. For the referring Board of Appeal, the factual and legal assessments made in the referring decision to the EBA were binding on it. In the referring decision the Board of Appeal had concluded that, if it was permissible to consider the post-published filed evidence by the patentee, the technical effect relied on for inventive step was credible. The Board of Appeal concluded that it could not later change this decision, even in the face of contradictory evidence later submitted by the opponent after G 2/21 had been decided. 

By contrast, the present case considered directly the question of credibility in the face of contradictory post-published evidence for and against a purported technical effect. In this case, the Board of Appeal concluded the patentee’s positive evidence for the technical effect supported inventive step, even in the face of the opponent’s contradictory evidence. In doing so, the decision in T 0629/22 confirms that the credibility/plausibility test is fairly low. The credibility/plausibility test is really just a test of whether a skilled person would have substantiated doubt, in view of common general knowledge and the application filed, that the claimed invention would have the purported technical effect (IPKat). Demonstrating the technical effect by one experimental method was considered by the Board of Appeal in T 0629/22 to satisfy this test. 

Viewed another way, the decision in T 0629/22 confirms that the technical effect of a claim may be adjusted post-hoc according to the experimental evidence available. Arguably, in this case, the technical effect was achieving melt-string characteristics as measured by a fork. However, the use of a fork to measure stretch was not specified in the description. T 0629/22 thus supports the interpretation of G 2/21 that explicit disclosure of the technical effect eventually relied on for inventive step is also not required (T 0116/18). 

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