G 1/23: Reductio Ad Absurdum

The reductio ad absurdum logical argument is a well known way of disproving an initial statement by showing that it leads to an absurd conclusion. If the initial statement is either true or false, the argument when properly applied inevitably leads to the conclusion that the opposite must be true. A well known application of the argument is the proof that there are infinitely many prime numbers, which dates back to ancient Greek times and is attributed to Euclid. The proof starts by assuming there are infinitely many prime numbers and figuring out the consequences. Following a series of logical steps, it can be clearly shown that the statement cannot be true because there is a number that is the product of all primes plus 1 that is either itself prime or cannot be divided by any prime, meaning there must be a prime number greater than all the primes initially assumed. Therefore, the initial assumption must be wrong and there must instead be infinitely many prime numbers. 

I have never before seen this type of argument being used in legal decisions, probably because legal analysis is typically quite different and is rarely as clear cut as to be amenable to logical proof. The recent decision of the Enlarged Board of Appeal in G 1/23 is the first example I am aware of that actually uses this argument, which it does in coming to an apparently definitive answer to the question of whether a product that is put on the market must be reproducible by the skilled person to be considered part of the state of the art. 

The argument is used by the EB to reject an interpretation of the prior decision G 1/92 that a non-reproducible product would be entirely excluded from the state of the art. The EB first assumes that this interpretation of G 1/92 is true, i.e. that a product put on the market, if not reproducible (i.e., the skilled person cannot manufacture it from scratch using different starting materials), is entirely excluded from the state of the art. This means the product, including all its properties, is treated as if it does not exist for the purposes of assessing novelty and inventive step under Articles 54(2) and 56 EPC (see point 44).

The EB then explores the logical implications of this assumption, focusing on the concept of reproducibility and the skilled person’s reliance on common general knowledge, which is derived from the state of the art (points 50–54). The skilled person’s common general knowledge is limited to what is part of the state of the art. If non-reproducible products are excluded from the state of the art, they cannot be part of the skilled person’s common general knowledge (point 57). The EB interprets “reproduce” as manufacturing the product by a different route, not simply obtaining it from the market (point 38). Thus, the skilled person must rely on starting materials that are themselves reproducible and part of the state of the art to recreate the product (point 58). To reproduce a product, the skilled person must use starting materials that are reproducible. However, these starting materials themselves require precursor materials, which must also be reproducible, and so on (point 59). This creates a regress where every material must be reproducible without relying on merely available (but non-reproducible) materials, such as naturally occurring substances or chemical elements (point 60). The EB then argues that this assumption leads to an absurd result: if only reproducible materials can be considered part of the state of the art, then no material in the physical world would qualify as state of the art. This is because all materials ultimately rely on non-reproducible starting materials, such as chemical elements or naturally occurring substances like crude oil, which cannot be synthesized from scratch by the skilled person (points 60–63). For example, chemical elements (e.g., carbon, oxygen) cannot be reproduced; they are taken from nature or the market. Even simple compounds or raw materials (e.g., crude oil) are not trivially reproducible, yet they are undeniably part of the technical reality the skilled person works with (point 61). If non-reproducible products are excluded, the state of the art becomes an “empty set” (point 65), meaning that no technical teachings, whether from products, documents, or oral disclosures, could be considered prior art, as they all depend on non-reproducible materials at some point. This outcome is described as “manifestly absurd” (point 72) because it contradicts the practical reality that skilled persons routinely use commercially available or naturally occurring materials in their work (point 67). Since the assumption that non-reproducible products are excluded from the state of the art leads to the absurd conclusion that the state of the art is empty, the assumption must be false. Therefore, the EB concludes that a product put on the market cannot be excluded from the state of the art solely because it is not reproducible (point 80). Instead, the product and its analysable properties are part of the state of the art, regardless of reproducibility, as long as they are publicly available (Headnote I and II). As a result, the EB reinterprets G 1/92 to align with this conclusion, concluding that “reproducibility” should include obtaining the product from the market in its readily available form, rendering the enablement requirement redundant (point 73). This ensures that commercially available products, even if not reproducible by manufacturing, are part of the state of the art, and their analysable properties can be considered for novelty and inventive step assessments (point 74).

The reductio ad absurdum argument used by the EB is effective here because it shows that the enablement requirement, as suggested by an interpretation of G 1/92, leads to an impossible and impractical outcome, which would exclude all materials from the state of the art. This contradiction with technical reality and the purpose of patent law (to assess inventions against what is publicly available) forces the rejection of the enablement requirement for products that have been put on the market. The argument underscores that the state of the art should include all publicly available technical information, regardless of whether the skilled person can replicate the product from scratch.