An exercise in fishing: no discovery of inventor’s notes in Australian biosimilar patent spat

In the latest saga over BRENZYS (active ingredient etanercept) – a biosimilar of Pfizer’s ENBREL used to treat autoimmune diseases - Samsung Bioepis (and others) has lost its application for discovery of inventor’s notes alleged relevant to inventive step.


Historically in Australia, discovery of documents concerning the development of an alleged invention, including inventor’s notes, has been considered as habitually allowed. This is provided that they are directly relevant to an issue raised by the pleadings based on the principles in Wellcome (Wellcome Foundation Limited v V.R. Laboratories (Aust) Pty Ltd (1981) 148 CLR 262). 

However, where Samsung Bioepis’ lack of inventive step case extended to a “welter” of combinations of prior art, Burley J considered that the discovery application was an impermissible fishing exercise (Pfizer Ireland Pharmaceuticals v Samsung Bioepis AU Pty Ltd (No 4) [2024] FCA 678) that was not relevant to the pleaded case.

His Honour did allow discovery directed at the best method known to the patentee, in circumstances where a named inventor had given evidence that tended to suggest the patentee agreed it had not done so. 


Following a series of preliminary discovery applications, in May 2022, Pfizer commenced proceedings in the Federal Court of Australia against Samsung Bioepis, Merck, Sharp & Dohme, Organon and Arrow (the Respondents).  

Pfizer contends that the Respondents’ manufacture and use of etanercept infringes its patent,  AU 2005280034, entitled “Production of polypeptides” (the Patent).

The Respondents have crossed claimed, saying that the Patent is invalid on various grounds including for lack of inventive step and failure to disclose the best method.

This decision concerns the Respondents’ application for non-standard discovery, namely:

  1.  All documents created from 27 August 2002 until 27 August 2004 recording or evidencing research, development or experimental work on the subject invention (Category 1); and
  2. All documents created before the Filing Date concerning the production of etanercept as described in example 16 of the Patent (Category 2).

The broader proceedings are listed for hearing for three weeks in September and October 2025. The parties are due to file their evidence in chief at the end of this year.


Category 1

In Australia, whether an invention is obvious is “an objective test, based on the imputed skills and knowledge of a notional person, which is a remove from the steps taken by the inventors themselves.”

The Respondents’ obviousness case was put on the basis of common general knowledge alone, but also a “welter” of combination of prior art documents – adding up to more than 80 variations. 

His Honour criticised the many ways that the Respondents put their obviousness case. He said it was a “poorly focussed, scattergun approach” and in such circumstances, found that the relevance of the inventor’s own path as “truly secondary”.  

“The relevance of Wellcome style discovery will vary from case to case.  In the event that the patentee chooses to give evidence of the inventive steps involved leading to the invention, then the relevance of such documents is likely to be elevated. In other cases, there may be particular indications that the inventors took a certain route to the invention that warrant the provision of discovery”, he said.

His Honour found that “…the pleading gives no inkling that it is relevant at all”… it “is no more than an exercise in fishing”. 

However, his Honour indicated that he would be willing to order discovery of these type of documents in the future in certain circumstances, such as  if the patentee provides evidence of the inventors’ steps.

Category 2

The Respondents’ pleaded case includes a further invalidity ground that the Patent does not disclose the best method of producing a polypeptide. This is because the best method is said to be described in Example 16 in the Patent, but this example is deficient, or omits certain information known to the patentee at the time of filing the application. 

Here the Applicant relied on evidence of  one of the co-inventors of the invention, given in response to a similar complaint in European proceedings seeking to challenge a related patent.  The effect of that evidence was that the broader disclosure in the Patent supports its argument that the best method was disclosed. 

His Honour found that this evidence tended to suggest that the patentee agreed that Example 16, of itself, was deficient in information, as pleaded. Consequently, his Honour was satisfied that the patent applicant may have information to correct that deficiency, and that discovery was warranted (with minor amendments to the category proposed).   

Key takeaways

This decision is a reminder that modern principles of discovery and the overarching purpose of civil practice and procedure (ie. seeking to resolve disputes as quickly, inexpensively and efficiently as possible) have overtaken the principles in Wellcome. The relevance of the inventor’s own path will be considered secondary unless it is put into issue by the patentee. 

As such, if inventor’s notes are not “directly relevant” to the issues raised by the pleadings or the evidence, they are not likely to be discoverable.