High Court Clarifies the Principles for Preliminary Discovery – Weight of Expert Evidence

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The High Court has rejected granting special leave to Samsung Bioepis (‘SB’) to challenge the decision of the Full Federal Court in Pfizer Ireland Pharmaceuticals v Samsung Bioepis AU Pty Ltd [2017] FCAFC 193. The High Court’s rejection, and the chain of litigation prior to it, have helpfully clarified the weight to be given to expert evidence in applications for preliminary discovery.


In 2017, Pfizer, a pharmaceutical manufacturer, brought an application for preliminary discovery of confidential documents belonging to Samsung Bioepis (‘SB’) – one of its competitors. Pfizer believed the documents would assist Pfizer in deciding whether to commence proceedings for patent infringement against SB.

Pfizer’s general counsel, Mr. Silvestri, gave evidence about his belief that Pfizer may have the right to obtain relief for patent infringement. Mr. Silvestri based his belief on the evidence of Pfizer’s expert witness, Dr Ibarra, regarding the “biosimilarity” between Pfizer and SB’s products, and the likelihood that this arose from a similarity in process used by both companies. [1]

SB engaged its own expert witness, who argued that the similarities could have been brought about by other matters, unrelated to patent infringement – namely matters involving other stages in the development of biological medicines. Hence, SB argued that Mr Silvestri’s evidence was not sufficient to lead one to reasonably believe that it may be infringing Pfizer’s patents. [2]

Decisions of the Courts

At first instance, Judge Burley in the Federal Court refused Pfizer’s application. He resolved the issue by reference to the expert witness’ competing views, and by rejecting the views of Pfizer’s expert, Dr Ibarra, as not ‘persuasive’. [3] Judge Burley had found that Pfizer’s expert evidence did not support a reasonable belief that SBA’s biosimilarity was patent infringing but amounted to ‘mere speculation’.

However, on appeal, the Full Federal Court allowed Pfizer’s application. Overturning Judge Burley’s decision, the Full Court found that he had erred in considering which party’s expert evidence was more persuasive or preferable. The proper inquiry, the justices said, was whether Pfizer’s evidence was capable of providing grounds for a reasonable belief that SBA may be infringing: [4]

“The primary judge approached the matter by asking himself the wrong question. It was not a matter of which body of expert evidence to prefer; rather, it was whether Pfizer reasonably believed that it may have a right to relief”, the Full Court ruled. [5]

Therefore, the relevant question was not whether one expert’s view is more or less persuasive, but rather whether Dr Ibarra’s views so lacked foundation that Mr. Silvestri’s reliance on them would not demonstrate that he reasonably believed that Pfizer may have a right to relief. As Dr Ibarra’s views were not criticised to this extent, this question was answered in the negative.

The Full Federal Court allowed Pfizer’s appeal, with the High Court allowing this decision to stand.


The decision of the Full Federal Court emphasizes that preliminary discovery applications are not intended to be “mini trials” that make a definitive decision on the value of expert evidence. Rather, in these preliminary stages, the Court must focus on what ‘may’ be the position and whether an applicant has a reasonable belief in a right to relief – not what ‘is’ the case. [6]


[1] Jones Day, ‘High Court of Australia Settles Principles for Preliminary Discovery ’ on Jones Day, Jones Day Publications (June 2018) <http://www.jonesday.com/high-court-of-australia-settles-principles-for-preliminary-discovery-02-05-2018/#>

[2] Ibid.

[3] Ibid.

[4] Ibid.

[5] Christine Caulfield, ‘High Court lets stand Pfizer’s early discovery win’ on Lawyerly, Intellectual Property (June 2018)  <https://lawyerly.com.au/high-court-dismisses-application-special-leave-samsung-bioepis-case-pfizer-ireland/>

[6] Above n 1

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