What is patent claim construction essentially about?

Anyone familiar with patents in the life sciences space will be familiar with patent claims that use terminology such as “essentially”, “therapeutic agent” and “about”. The familiarity of such terms means that they are often recited without much consideration. However, their meaning was in issue in the recent decision in Pharmacia LLC v Juno Pharmaceuticals Pty Ltd [2022] FCA 92.

Claim 1 of the patent in issue recited, in part, “A pharmaceutical composition comprising… (a) at least one water-soluble therapeutic agent…in a therapeutically effective total amount constituting about 30% to about 90% by weight…”. Further, claim 11 recited a composition “that consists essentially of the therapeutic agent and the buffering agent”.

In his reasons Justice Burley made light work of the construction of “essentially”. Whilst essentially is a relative term, it was given its ordinary meaning of “mostly”, but not exclusively, which was consistent with its use in the claims and the specification. The terms “therapeutic agent” and “about” required a little more consideration.

The claims encompassed a pharmaceutically active parent compound (in the form of a prodrug) or a sodium salt of the parent compound. Because the sodium salt of the parent compound is heavier than the parent compound alone, it needed to be determined if the claimed weight range of the “therapeutic agent” related to the parent compound only or could also relate to the salt. With reference to the specification, Justice Burley determined that either the sodium salt or the parent compound alone can be regarded as therapeutic agents even though only the parent compound exerts a therapeutic effect. Hence a composition having 31% of the sodium salt would fall within the claimed range of 30% to 90% for the “therapeutic agent” even though the percentage (by weight) of the pharmaceutically active component (i.e. the parent compound) was less than 30% when the weight of the sodium is disregarded.

The term “about”, like “essentially”, is a relative term. In the context of the patent claims it was used to define the weight ranges of the various components of the composition. Justice Burley was asked to determine if “about” should allow a 5% margin of error (i.e. “to 90%” would become “to 94.5%”) or should only allow for rounding to the nearest number (i.e. “to 90%” becomes “to 90.49%”). It was agreed by both sides that the term “about” was not a term in the precise field of pharmaceutical sciences and therefore was “mostly avoided”. Consequently, the experts assisting the court struggled to give relevant meaning to the term. Justice Burley turned to the ordinary English meaning of the term (“near; close to”) and the use of the term in the patent specification. Notably, the term was not defined in the specification. Therefore, the applicants asserted that specific examples and disclosures in the specification supported the broader 5% margin of error. However, Justice Burley did not agree that the passages cited by the applicants clearly supported the broader range. He further stated that it could not be the intention of the inventors for the meaning of the word “about” to be mined from obscure passages in the specification, nor could such obscurity provide sound basis for construing a claim. Ultimately, the term “about” was narrowly construed to allow for rounding errors only (i.e. “to 90%” was considered as “to 90.49%)

In comparison the term “about” was briefly considered in Meat & Livestock Australia Limited v Cargill, Inc [2018] FCA 51, also in relation to a claimed numerical range. Here Justice Beach construed “about” as providing a 10% margin of error. Importantly, unlike the present case, the specification clearly defined “about” as meaning ±10%.

While it is common to use relative or imprecise terminology in claims, this should be done with caution. Typically, these terms are used as a fallback allowing extension of the claimed boundaries, which may provide utility if a potential infringing act or product arises. However, as exemplified with the term “about” this extension of the boundaries may be limited and may vary depending on the technical field of the invention.

BMedPharmBiotech(1st Class Hons) PhD MIPLaw

Prior to joining Phillips Ormonde Fitzpatrick, Leigh worked as a post-doctoral research fellow at Harvard University in the department of Stem Cells and Regenerative Biology and the department of Molecular and Cellular Biology. Leigh has liaised and collaborated with researchers and research teams across a multitude of research facilities, including Massachusetts Institute of Technology, Brigham and Women’s Hospital (Boston), Dana Farber Cancer Centre (Boston), University of Adelaide, Hanson Institute and the University of South Australia.