"Disclaimer" amendments are useful, particularly where the key objection is novelty. Applicants usually limit the claim by falling back on pre-prepared positions set forth in subclaims or in the description, usually defined in "positive" terms (i.e. requiring the presence of a feature). In contrast, a disclaimer limits the claim by excluding what is taught in the prior art, using "negative" terminology (i.e. requiring the absence of a feature), which can often leave broader protection.
However, as always, it is necessary to bear in mind that European patent law prohibits making amendments which result in new subject matter not taught in the application as filed. When coupled with the ban on post-grant broadening amendments, this can leave applicants caught in an inescapable trap. Several previous EPO decisions have considered the circumstances under which certain types of disclaimer avoid the trap - or fall into it.
The EPO Enlarged Board of Appeal recently gave its decision in G 2/10 regarding the allowability of an amendment to disclaim subject matter that was disclosed as an embodiment of the invention.
Decision G 1/93 held that, where an undisclosed limiting feature - without providing a technical contribution to the subject-matter of the claimed invention - merely excludes protection for part of the subject-matter of the claimed invention, it did not add matter. Decisions G 1/03 and G 2/03 set out the criteria for assessing whether such "undisclosed disclaimers" are allowable. Following G1/03, a disclaimer amendment to a claim may be allowable in order to:
(a) restore novelty with respect to the state of the art under Art 54 (3) EPC;
(b) restore novelty to overcome an accidental anticipation under Art 54 (2) EPC; and
(c) remove subject matter which, under Art 52 to 57 EPC, is excluded from patentability for non-technical reasons.
These decisions dealt with the situation where the feature added to the claim excluded the prior art - either by reciting the absence of the feature disclosed in the prior art and not the patent, or the presence of the opposite (as in the archetypical case T 0073/88 HOWARD/Snackfood in which the undisclosed limitation to "containing at least 5% by weight of oil or fat" was added to overcome prior art containing less than that). They found, essentially, that "undisclosed" disclaimers of this type were allowable if they did not combine with the features of the invention, and if the disclaimer went no further than was necessary to achieve its legitimate purpose (i.e. one of those set out above).
The application in question in G2/10 related to catalytic or enzymatic DNA molecules that are capable of cleaving nucleic acid sequences or molecules, in particular RNA, in a site-specific manner. During examination, the claims of the application were amended to introduce undisclosed disclaimers (i.e. negative features that were not disclosed in the application as originally filed), to exclude subject matter that was previously disclosed in the prior art. The application was refused during examination for the reason that the disclaimer did not meet the requirements as set out in G 1/03 and G 2/03.
The applicants filed an appeal, and replaced the undisclosed disclaimer with a limitation to disclaim molecules that were originally disclosed as an embodiment of the invention. This therefore differed from the previous cases, in which the disclaimer and the disclaimed matter were not disclosed in the application, and the EPO case law diverged on whether such amendments were always allowable, never allowable, or allowable depending on the facts.
The Technical Board of Appeal therefore referred the following question to the Enlarged Board of Appeal:
"Does a disclaimer infringe Art 123(2) EPC if its subject matter was disclosed as an embodiment of the invention in the application as filed."
In summary, the Enlarged Board of Appeal answered the question referred to it as follows:
1a. An amendment to a claim by the introduction of a disclaimer disclaiming from it subject matter disclosed in the application as filed infringes Art 123 (2) EPC if the subject matter remaining in the claim after the introduction of the disclaimer is not, be it explicitly or implicitly, directly or unambiguously disclosed to the skilled person using common general knowledge, in the application as filed; and
1b. Determining whether or not that is the case requires a technical assessment of the overall technical circumstances of the individual case under consideration, taking into account the nature and extent of the disclosure in the application as filed, the nature and extent of the disclaimed subject-matter and its relationship with the subject matter remaining in the claim after amendment.
There were submissions from the parties and the EPO, and various amicus briefs. One theory was that, where an application made a generic disclosure X and also made a specific disclosure Y within the genus, then the result was that it disclosed not only X and Y, but also (X-Y) - i.e. everything but the preferred embodiment. On this basis, disclaiming a preferred embodiment would never add matter, and would always be allowable, as a question of logic.
The Enlarged Board held that the findings of the earlier Enlarged Board decisions above concerned the specific case of justified, narrow, undisclosed disclaimers. The present case, however, was to be dealt with using the normal rules of disclosure - when disclaiming Y, the question was, as a matter of fact, did the application as filed disclose (X-Y), and the answer could not be presumed to be either yes or no.
Why might an applicant want to disclaim specific embodiments disclosed in the application? In situations where sequential applications have been filed for related or overlapping subject matter, it may be necessary to disclaim subject matter disclosed in an earlier application, in order to avoid anticipating the subject matter in a later application.
In practical terms, this may be problematic in situations where a product is still in development and a patent application is drafted with broad claims to maximise the scope of protection. Subsequent patent applications may be filed at a later stage of development, to define the product more precisely, and the possible requirement to disclaim subject matter disclosed in the earlier application should be considered.
Overcoming prior art is only one reason. As the Enlarged Board pointed out, it may also be desirable to split an application, perhaps prosecuting the original application to the preferred embodiment and filing a divisional to protect the rest in slower time, or perhaps for licensing reasons. They suggest that such procedural behaviour is not abusive and even legitimate." Disclaimers enable the applicant to avoid double patenting whilst leaving no gaps in cover.
As always, therefore, great care must be taken to avoid adding matter on amendment. When drafting a patent application, it is advisable to consider future applications which will relate to similar subject matter. When drafting second and subsequent applications in a sequence, care should be taken to avoid known prior art documents and, if possible, basis should be provided in the application that will allow the introduction of a disclaimer, if required, at a later stage