Clarification of disclaimer practice at the EPO

In its recent G 1/16 decision, the European Patent Office (EPO) Enlarged Board of Appeal clarified how disclaimers should be examined. While undisclosed disclaimers must meet the four-step test set out in G 1/03, disclosed disclaimers must comply with the 'gold standard' of G 2/10. Despite this clarification, disclaimers still present significant risks in Europe and should be used cautiously.

A ‘disclaimer’ is a negative claim limitation, typically excluding specific embodiments or areas from the scope of a claim (eg, a claim with the following disclaimer: "A metal, wherein the metal is not steel”).

At the EPO, disclaimers are categorised as either disclosed or undisclosed, depending on whether the disclaimed embodiment is mentioned in the application. The above example would be an undisclosed disclaimer if the application made no mention of steel. However, if the application mentioned steel (eg, “in some embodiments, the metal of the invention is not steel”), then the disclaimer would be a disclosed disclaimer. Under some circumstances, a disclosed disclaimer may also be based on a positive statement, such as “in some embodiments, the metal of the invention is steel”.

G 1/03: undisclosed disclaimers
In 2004 the Enlarged Board of Appeal in G 1/03 set out the following four-step test for undisclosed disclaimers:

  • Is there a suitable reason for a disclaimer?
  • Does the disclaimer remove no more than is necessary?
  • Is the disclaimer unrelated to inventive step and sufficiency?
  • Is the disclaimer clear and concise?

To permit an undisclosed disclaimer, the answer to each question must be ‘yes’.

Step 1 is passed if the need for the undisclosed disclaimer arises because of one of three suitable reasons set out in G 1/03:

  • removing subject matter excluded from patentability in Europe (eg, methods of treatment);
  • establishing novelty over a novelty-only prior art document (at the EPO, this would include an earlier-filed European patent application that was published after the effective filing date); and
  • restoring novelty over an accidental anticipation.

To qualify as an accidental anticipation, the prior art disclosure “must be so unrelated and remote that the person skilled in the art would never have taken it into consideration when working on the invention”.

Step 2 is passed if the disclaimer is no broader than is required to:

  • remove the subject matter excluded from patentability;
  • establish novelty over a novelty‑only prior art document; or
  • restore novelty over an accidental anticipation (as appropriate).

Step 3 is passed only if the disclaimer has no impact on inventive step or sufficiency – for example, if an undisclosed disclaimer not only establishes novelty over an accidental anticipation, but also improves the position on inventive step relative to another piece of prior art, then it fails Step 3.

Step 4 is passed if the disclaimer is drafted clearly and concisely. The second and fourth-step requirements can sometimes conflict – for example, if a novelty‑only prior art discloses an embodiment in an unclear manner, then disclaiming no more than necessary (as required by Step 2) could result in the disclaimer also being unclear, thereby falling foul of Step 4. The EPO Guidelines for Examination suggest that the EPO may permit an applicant to escape this trap by removing more than is necessary from a claim for the sake of clarity or brevity.

G 2/10: disclosed disclaimers
In 2010 the Enlarged Board of Appeal was asked to consider whether a disclaimer adds matter if its subject matter was disclosed as a positive embodiment of the invention in the application – for example, could an applicant disclaim ‘steel’ from ‘metal’ based on the following positive statement in the application: “In some embodiments, the metal of the invention is steel.”

In G 2/10 the Enlarged Board of Appeal held that a disclosed disclaimer is permitted if the subject matter remaining in the claim after the introduction of the disclaimer is explicitly or implicitly, directly and unambiguously disclosed to the skilled person using common general knowledge in the application as filed – this is known as the ‘gold standard’.

Determining whether an amendment meets the gold standard requires a technical assessment of the overall technical circumstances of the case that considers:

  • the nature and extent of the disclosure in the application; and
  • the nature and extent of the disclaimed subject matter and its relationship with the subject matter remaining in the claim after the amendment.

Does G 2/10 apply to undisclosed disclaimers?
G 2/10 contains several general statements that suggest that the gold standard test is applicable not only to disclosed disclaimers, but also to amendments in general. Therefore, it was unclear whether an undisclosed disclaimer must meet the requirements of:

  • the G 1/03 four-step test;
  • the G 2/10 gold standard; or
  • both tests.

Divergent opinions were forwarded by the Technical Boards of Appeal in subsequent decisions. The latest version of the Guidelines for Examination appeared to endorse the application of both tests to undisclosed disclaimers.

G 1/16
In T 437/14 the Technical Board of Appeal considered there to be sufficient uncertainty surrounding this issue to warrant a referral to the Enlarged Board of Appeal, which is how G 1/16 originated. The claim considered in T 437/14 contained two undisclosed disclaimers that addressed accidental anticipations. The Technical Board of Appeal held that the disclaimers met the requirements of the G 1/03 four-step test, but failed the G 2/10 gold standard because the subject matter remaining in the claim was not directly and unambiguously disclosed in the application as filed. It also held that it may need to apply both tests, but was unsure how to do this. Therefore, it referred the following questions to the Enlarged Board of Appeal:

  • Is the G 2/10 gold standard applicable to claims containing undisclosed disclaimers?
  • If the answer to this question is ‘yes’, is G 1/03 set aside?
  • If the answer to the second question is ‘no’, may the gold standard be modified in view of G 1/03?

In G 1/16 the Enlarged Board of Appeal held that undisclosed disclaimers must satisfy only the G 1/03 four-step test (ie, the G 2/10 gold standard does not apply to undisclosed disclaimers), thus the answer to the first question is ‘no’.

The main reason for the Enlarged Board of Appeal’s decision was that applying G 2/10 to undisclosed disclaimers would leave “virtually no chance of an undisclosed disclaimer being allowable”, because:

where an undisclosed disclaimer is introduced into the claim it (almost) automatically follows that the subject matter remaining in the claim after the introduction… can hardly be considered to have been explicitly or implicitly, and directly and unambiguously, disclosed in the application as filed”.

The G 1/16 decision clarified which test applies to each type of disclaimer recognised in Europe. Disclaimers should nevertheless still be used with caution. If a disclaimer is judged to add matter post-grant, it will often be impossible to remove the disclaimer without impermissibly broadening the scope of the granted claim.

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