Disclaimer amendment allowed in mastitis patent

Date: 25 November 2021
Court:  Federal Court of Australia
Judge: Besanko J

Background

This appeal from a decision of the Australian Patent Office concerned the allowability of amendments to the claims of Australian Patent Application 2009304000 (Application) relating to an antiseptic formulation for treating mastitis in cattle. The key amendment to claim 1 was a disclaimer that the antiseptic is not an ‘acridine’, introduced by the patent applicant (Elanco) to avoid a novelty objection upheld in an opposition to the Application.

The opponent (Boehringer) opposed the amendment on the ground that amended claim 1 would claim matter not in substance disclosed in the specification. The Patent Office found that there was a real and reasonably clear disclosure in the specification of the matter claimed, i.e. the treatment of mastitis in cattle using an antiseptic that is not an acridine, and allowed the amendment. Boehringer appealed.

Key Issues

Besanko J’s review of the case law showed that, although there is no automatic rule that amendments limiting the scope of a claim are allowable, this will usually be the case because the specification will usually provide a real and reasonably clear disclosure of what is left within the claim. However, the case law contemplated two potential exceptions to that rule, first, an amendment to narrow to a specific embodiment where the specification describes an invention only very generally, and second, an amendment to disclaim an embodiment which the specification recommends or prefers.

Boehringer’s case was that, as a consequence of the first exception, the amendment could only be sustained if there was a positive disclosure that acridines were not to be used. Moreover, it argued that acridines were a preferred embodiment in the specification and therefore an amendment to disclaim them should not be allowed under the second exception. Although none of the antiseptics named in the specification (one of which, chlorhexidine, was clearly the most preferred) were acridines, Boehringer relied on a statement in the specification that the antiseptic preferably had one or more of six desirable properties. Two classes of antiseptics were exemplified as having one or more of these properties, ionised antiseptics (IAs) and quaternary ammonium compounds (QACs). Boehringer contended that acridines had one or more of the desirable properties, and that acridines were IAs or QACs. On either basis, acridines were preferred.

Outcome

Besanko J rejected the first argument as inconsistent with the authorities. Specifically, it is not necessary for the specification to disclose that a particular embodiment (in this case, acridines) is not to be used in the invention for an amendment to disclaim that embodiment to be allowable.

As to the second argument, of the six expert witnesses, two considered that the specification preferred only the four named antiseptics (Interpretation 1), two considered that it preferred any antiseptic with one or more of the desirable properties (including IAs and QACs) (Interpretation 2), and two considered both views reasonable but favoured Interpretation 1. The evidence established that a large number of antiseptics had the desired properties, and that some antiseptics with the desired properties would otherwise be unsuitable for use in the invention.

The evidence also established that IAs and QACs include acridines but that thousands of compounds other than acridines are IAs and QACs. Therefore, a reference to IAs or QACs could not be treated as a reference only to acridines or as a reference to all acridines. In other words, there was no correspondence between the terms. Further, the evidence demonstrated that it was not generally known amongst those skilled in the art that acridines were IAs or QACs. Therefore, even if the specification did prefer IAs or QACs, those skilled in the art would not have understood this as a preference for acridines.

For these reasons, the judge concluded that the specification did not express a preference for acridines, so the amendment to disclaim acridines from the scope of claim 1 was allowed.

Implications

The judgment confirms that amendments to disclaim certain embodiments from the scope of claims will only be considered unallowable in specific circumstances. Where an opponent to such an amendment contends that the specification prefers the embodiment so it cannot be disclaimed, they will need to identify a clear preference for that embodiment in the specification, for example, that the embodiment is one of a limited number identified by name. If the embodiment is not identified by name, it is unlikely to be considered to be preferred only on the basis that it is one of a large number of embodiments for which some preference is expressed. The embodiment is also unlikely to be preferred if it has properties which the specification states are undesirable in relation to the invention.