When the claims of a European patent application or patent are amended, the amended claims must satisfy Article 123(2) EPC in order for them to be allowable. Article 123(2) EPC specifies that the European patent application or European patent may not be amended in such a way that it contains subject-matter which extends beyond the content of the application as filed. The European Patent Office (EPO) is well-known for its strict approach in making this assessment. The “gold standard”, frequently cited in EPO case law, requires that an amendment can only be made within the limits of what the skilled person would derive directly and unambiguously, using common general knowledge, from the application as filed (see G 3/89, G 11/91, G 2/10).

One way of amending a claim to restore novelty over a prior art document is to explicitly state in the claim that certain subject-matter is excluded. These statements, known as “disclaimers”, are most often used in the chemical and pharmaceutical fields, for example to exclude a particular compound or narrow group of compounds from a broad claim. The bulk of EPO case law concerning disclaimers relates to one of the following two classes of disclaimer:

  • a “disclosed disclaimer”, in which the excluded subject-matter is disclosed as a positive feature in the application as filed but the disclaimer itself is not (e.g. the disclaimer is “not A”, and the application as filed does not disclose “not A” but “A” is disclosed as a positive feature); and
  • an “undisclosed disclaimer”, in which neither the disclaimer nor the excluded subject- matter is disclosed in the application as filed (e.g. the disclaimer is “not A”, and neither “A” nor “not A” are disclosed).

A further type of “disclosed disclaimer”, not considered here, is one in which the disclaimer itself (e.g. “not A”) is disclosed in the application as filed.

The allowability of “undisclosed” disclaimers was analysed in G1/03, which set out circumstances in which undisclosed disclaimers can be used. These circumstances (given in answer 2.1 of G1/03) included restoring novelty over a novelty-only prior art document (Article 54(3) EPC) or an accidental anticipation, i.e. an anticipation “so unrelated and remote that the person skilled in the art would never have taken it into account when making the invention”. G 1/03 therefore allowed, in limited circumstances, an amendment to be made that would otherwise fall foul of the EPO’s strict added subject-matter provisions under Article 123(2) EPC.

The apparent conflict between “undisclosed” disclaimers and Article 123(2) EPC has yet to be fully resolved, and in recently-issued decision T 437/14 the question has arisen as to whether the “gold standard” referred to above must also be applied to undisclosed disclaimers that would otherwise be allowable under G 1/03. In particular, the Board of Appeal in T 437/14 notes that while Enlarged Board decision G 2/10 held that the “gold standard” applies to “disclosed” disclaimers (see above), the issue has yet to be settled for “undisclosed” disclaimers. Accordingly, the Board in T 437/14 has made a referral (which will presumably be numbered G1/16) to the Enlarged Board to decide the following questions:

“1. Is the standard referred to in G 2/10 for the allowability of disclosed disclaimers under Article 123(2) EPC, i.e. whether the skilled person would, using common general knowledge, regard the subject-matter remaining in the claim after the introduction of the disclaimer as explicitly or implicitly, but directly and unambiguously, disclosed in the application as filed, also to be applied to claims containing undisclosed disclaimers?

2. If the answer to the first question is yes, is G 1/03 set aside as regards the exceptions relating to undisclosed disclaimers defined in its answer 2.1?

3. If the answer to the second question is no, i.e. if the exceptions relating to undisclosed disclaimers defined in answer 2.1 of G 1/03 apply in addition to the standard referred to in G 2/10, may this standard be modified in view of these exceptions?”

It is clear from the decision in T 437/14 that the Board referring the questions is of the view that the answer to question 1 should be “yes”; in other words, that the “gold standard” should apply to undisclosed disclaimers. The Board goes on to suggest (point 8.1 of the reasons) that if the “gold standard” does apply, then undisclosed disclaimers will almost by definition fall foul of the added subject-matter provisions of the EPC. The Board illustrates this point with a simple example:

“…if one takes a bite out of an apple, what remains is recognisably no longer the same apple as the original one. Even though it is still an apple, the apple with the bite taken out of it cannot be regarded as explicitly or implicitly, but directly and unambiguously, “disclosed” in the original apple.”

While we will have to wait some time to hear the Enlarged Board’s decision on the matter, applicants should exercise caution in using undisclosed disclaimers in case the resulting amended claims are found to be invalid after the issuance of the Enlarged Board’s decision. In the meantime, it will be possible to request a stay of proceedings for cases before the EPO Examining and Opposition divisions whose outcome depends on the answers to the above questions.