Independent Lines of Reasoning: R 0018/23 on Causality in Petitions for Review
The Enlarged Board of Appeal clarifies how a procedural violation interacts with a decision resting on multiple lines of reasoning, emphasizing the lexical choices of the Technical Board of Appeal.
The doctrinal boundary between a Board of Appeal's legitimate evaluation of arguments and the ex officio introduction of new facts has shaped the right to be heard since the Enlarged Board of Appeal issued G 4/92. In R 0018/23, the Enlarged Board of Appeal revisits this boundary to clarify how a procedural violation interacts with a decision resting on multiple lines of reasoning. The petition for review arose from the revocation of EP 2 087 626 B1 by the Technical Board of Appeal in T 0522/21, where the patent proprietor alleged that the Board of Appeal introduced new factual assumptions regarding the sufficient disclosure of the priority document without giving an opportunity to comment.
How did a missing signalling mechanism trigger a procedural violation?
The dispute centered on whether the priority document provided a sufficient disclosure for a specific modulation signalling scheme. For the second embodiment, the Technical Board of Appeal concluded that it was unclear how a user equipment was informed that certain channelization codes were restricted to odd numbers. The patent proprietor argued that this concern was never raised by the opponents and was introduced ex officio only in the written decision.
Applying the principles of G 4/92, the Enlarged Board of Appeal agreed that the Technical Board of Appeal had introduced a new factual assumption: namely, that a mechanism for communicating the restriction to the user equipment was necessary to implement the embodiment. Because this factual assumption was not discussed in the appeal proceedings, the Enlarged Board of Appeal found that the petitioner's right to be heard under Article 113(1) EPC was violated.
Why did the Enlarged Board of Appeal find no causal link to the revocation?
Despite finding a violation of the right to be heard, the Enlarged Board of Appeal rejected the petition for review filed under Article 112a(2)(c) EPC. A procedural violation is only fundamental if there is a causal link between the violation and the final decision.
The Enlarged Board of Appeal noted that the Technical Board of Appeal's finding on the second embodiment rested on two distinct lines of reasoning. The first line addressed how the parameters were encoded into the remaining bits. The second line addressed how the restriction to odd numbers was signalled to the user equipment. Because only the second line of reasoning was tainted by the procedural violation, the revocation would still stand on the first line alone, provided the two lines were genuinely independent.
How does the Enlarged Board of Appeal determine if reasoning lines are independent?
To assess causality, the Enlarged Board of Appeal had to determine whether the two lines of reasoning were independent or intertwined. The petitioner argued that the second line reinforced the first, meaning the tainted reasoning infected the entire conclusion.
The Enlarged Board of Appeal rejected this approach, holding that whether the two lines of reasoning are independent is to be ascertained from the perspective of the relevant Board of Appeal, through an analysis of the words it chose to use and without any review of the technical merits of the case (reasons 4.3.3). The Enlarged Board of Appeal observed that the Technical Board of Appeal introduced the second reason with the adverbs "also" and "moreover". The Enlarged Board of Appeal classified the ordinary function of these adverbs as paratactic, meaning they add or juxtapose independent thoughts rather than subordinating or reinforcing them. Because the Technical Board of Appeal presented the grounds as alternative and independent, the Enlarged Board of Appeal accepted them as such without reviewing the technical substance.
What must practitioners change when filing a petition for review after R 0018/23?
When a decision rests on multiple lines of reasoning, establishing a fundamental procedural violation requires proving that the violation taints every independent pillar supporting the conclusion. Practitioners generally cannot rely on a violation affecting only one alternative ground, even if that ground appears technically intertwined with the others.
Furthermore, R 0018/23 demonstrates that the Enlarged Board of Appeal relies heavily on the lexical choices of the Technical Board of Appeal. If a decision uses paratactic connectives like "also" or "moreover" to separate its arguments, the Enlarged Board of Appeal is likely to treat those arguments as legally independent. Petitioners must therefore carefully analyze the specific transitional words used in the written decision before committing to a petition for review.
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Further Reading
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