Implicit basis for disclaimers

A recent Board of Appeal decision, T 0273/22, gives more insight into the basis requirements for disclaimers.

Background

The case centred around whether “implicit basis” disclosed in the application was enough to support the disclaimer recited in the claims.

Disclaimers

Generally, claims define the invention in positive terms. However, it is also possible to define the invention in negative terms i.e., referring to features that are not present in the invention. This is achieved using disclaimers.

There are three circumstances under which a disclaimer can be introduced without adding matter:

1. Disclaiming subject matter which is disclosed as a positive feature in the application as filed. To be allowable, the subject matter remaining after the disclaimer is introduced must be explicitly or implicitly, directly, and unambiguously derivable from the application as filed (see G 2/10) (e.g., wherein A+B+C is disclosed a positive embodiment, but the applicant wants to disclaim feature C. To do this, there must be basis in the application for A+B alone without C). This is referred to as a disclosed disclaimer.
2. When neither the disclaimer itself nor the subject matter excluded by it is disclosed in the application, but an undisclosed disclaimers, is allowed under certain circumstances – as laid out by G 1/03. Namely, to restore novelty over a novelty only (Art. 54(3) EPC) disclosure, restore novelty over an accidental anticipation (i.e., prior art which is so far removed from the claimed invention that the skilled person would never have taken it into account) or removing subject matter excluded from patentability for non-technical reasons. The disclaimer may not be used to support an inventive step or address a lack of insufficiency and must be clear.
3. The negative feature is disclosed based on what skilled person would derive directly and unambiguously, using their common general knowledge, and seen objectively relative to the date of filing from the application as filed i.e., the so-called gold standard in the application as filed (e.g., wherein feature A “does not include feature B” is recited in the application as filed).

The decision

The patent EP2786657, a divisional application of EP2264163, was directed towards a method of producing an antibody comprising a human variable region and a rodent constant region, wherein said rodent does not produce fully human antibodies.

The disclaimer “wherein said rodent does not produce fully human antibodies” was introduced into claim 1 during prosecution to address a novelty objection.

The question during post-grant proceedings was whether this disclaimer had adequate basis in the application.

1. This was not a disclosed disclaimer – It was undisputed by all parties that there was no positive disclosure in the application of rodent producing fully human antibodies. As such, the disclaimer was not a disclaimer disclaiming subject matter which is only explicitly disclosed as a positive feature in the application as filed in the sense of G2/10 i.e., a disclosed disclaimer.
2. This was not an undisclosed disclaimer – It was also undisputed, by both the Board of Appeal and the patent proprietor, that this disclaimer did not satisfy the criteria, as determined by G 1/03, as the prior art in question was cited in the application itself and therefore could not be considered to be far removed from the subject-matter in question. As such, this was not seen as an undisclosed disclaimer.
3. Gold-standard disclaimer? – The proprietor argued that this disclaimer was implicitly disclosed in the application as filed. An implicit disclosure relates solely to matter which is not explicitly disclosed but is clearly and unambiguously derivable from what is explicitly mentioned in the application.

Firstly, the proprietor argued that the focus of the original disclosure was based on the production of hybrid antibodies comprising a human variable region and a rodent constant region. The proprietor argued that it was clear that these hybrid antibodies are not fully human. The Board agreed that a hybrid antibody was disclosed in the application. However, the Board found that this did not provide adequate basis for the disclaimer “wherein said mouse does not produce fully human antibodies”. They explained that the term “comprising” was used with reference to the hybrid mouse and therefore due to this language, it did not exclude mice that could have included further modifications so that they may produce both hybrid and fully human antibodies.

Additionally, the proprietor argued that the disclaimer “does not produce fully human antibodies” was implicit from the prior art disclosed in the background section of the application. In this section of the application, the proprietor referred to the disadvantages of the prior art, which utilised fully human antibodies.   The proprietor had hoped to convince the board that the skilled person would know, by comparing the advantages claimed invention with the prior art technology, that mice producing fully human antibodies were not an aspect of the invention.

The Board did not share this view. The Board found that there was a fundamental difference between (i) an implicit disclosure inferred by comparing the features disclosed in the prior art with the claimed invention VS what the skilled person would derive directly and unambiguously from the disclosure of the application and (ii) explicit, precise wording that a feature be absent in the claim. The board considered the implicit disclosure too vague and imprecise and would result in too many unanswered questions to provide adequate basis for the disclaimer.

Consequently, the Board concluded that the patent be revoked on the grounds of added subject-matter.

Practice points

The basis requirements for including negative features is the same as that for positive features. Both require “gold standard” disclosure i.e., what the skilled person would derive directly and unambiguously, using common general knowledge, and seen objectively and relative to the date of filing, from the whole of the application as filed.

It seems clear the Board take a very strict approach with regards to added matter and disclaimers. This suggests a strong area of attack for opponents during post-grant proceedings.

Moreover, this case emphasises the risk of including a disclaimer into the claims during prosecution to overcome prior art. It’s clear such disclaimers will likely be attacked during post-grant proceedings.

An implicit disclosure for a disclaimer does not arise merely by the mention of a prior art document in the description. Rather the skilled person must be able to determine the subject matter directly and unambiguously from the application as filed.

Explicit disclosure of the excluded subject matter is preferred (e.g., where feature A does not include feature B).