Patent decision reaches boiling point as claim is found invalid

A recent decision (Calix Limited v Grenof Pty Ltd [2023] FCA 378) from the Federal Court of Australia has reminded both IP attorneys and patent applicants of the importance of ensuring that a patent specification supports the claimed invention.

Background and claims

Calix is the Applicant for Australian patent No 2014339743 (the Patent) directed towards a process of producing hydroxide slurries. Calix alleged that Grenof infringed (and subsequently Aquadex) their patent by manufacturing, supplying and/or offering to supply a product (Phodine Plus and Phodine).

In response, Grenof denied infringement of the Patent. Grenof also cross-claimed that the Patent was invalid due to:

Thisisengineering Raeng Prfwu21zgqg Unsplasha. a lack of novelty;

b. a lack of inventive step;

c. the specification did not disclose the invention in a manner that was enough and complete enough for the invention to be performed by the person skilled in the art;

d. and that the claims were not supported by the matter disclosed in the specification.

During the case, Grenof contended that the process utilized to manufacture Phosdine Plus did not include the following steps of claim 1: ‘(b) applying a shearing force to the reaction mixture using a mixing apparatus’ and ‘(c) allowing heat of hydration to raise the temperature of the reaction mixture to near the boiling point’.

The issue debated was the use of the term ‘near the boiling point’. Both Grenof and Calix agreed that the term ‘near the boiling point’ referred to a temperature below, and not at or above, the boiling point. It was noted that the complete specification was a ‘confused and muddled document especially when regard is had to the temperature limitation (“near the boiling point”) referred to in claim 1’. In this regard, in some places of the specification, the specification speaks of controlling the temperature to just below or at the boiling point, whereas in other places it suggests that the water in the aqueous phase of the reaction mixture is allowed to boil.

Validity and outcome

Ultimately, the Federal Court found claim 1 did not involve an inventive step and was not supported by the matter disclosed in the specification. On the issue of support, the Federal Court found that the description of the invention as a whole did not support a claim where the maximum temperature of the reaction mixture is limited to ‘near the boiling point’. As such, the Federal Court found that claim 1 was fundamentally different from the invention disclosed in the specification and thus not supported.

This case highlights the importance of the written description. As such, it is of paramount importance that the written description is sufficient to support and sufficiently describe the invention because, as demonstrated by the present case, if not the claims can be found invalid. Care should be taken during prosecution to ensure that the claimed invention is supported by the subject-matter disclosed in the specification. Furthermore, care should be taken when drafting an application to ensure that all possible amendments are supported by the specification.

Our attorneys are highly experienced and successful in drafting patents which we’ve prosecuted through to grant in Australia (and in major overseas jurisdictions) for our clients. Please do not hesitate to contact us at Michael Buck IP for further information or if you require any assistance in protecting your intellectual property.


David Tso
written by David Tso, Senior Associate