Intricacies of Expert Evidence

27 November 2012

Howard Yap

Intricacies of expert evidence

The “intricacies” of one's expert evidence in patent invalidation proceedings can very well make or break your case. This is apparent from the decision in a Singapore High Court case, Martek Biosciences Corp v Cargill International Trading Pte Ltd [2012] SGHC 35.


The applicant (Martek) was the proprietor of a Singapore patent, which was revoked by the Deputy Registrar of Patents and the Principal Assistant Registrar of Patents (the Tribunal) upon an application of revocation by the respondent (Cargill).

Martek’s expert witnesses

During the revocation proceedings before the Tribunal, Martek had two expert witnesses, Dr Barclay and Dr Kyle. Dr Barclay had been Martek's Director of Discovery and chief Intellectual Property Officer for Martek since 1987. Cargill argued that Dr Barclay was not an objective witness because he was one of the founders of Martek and remains an employee and therefore had a direct commercial interest in the Patent. Dr Kyle was the sole inventor of the patent and had been employed by Martek since 1985 but left in 2001 to start his own company and therefore was no longer employed by Martek at the time of the hearing. Cargill argued that Dr Kyle could not be considered an objective witness because he was the sole inventor of the patent and therefore had an interest in the patent. For both Dr Barclay and Dr Kyle, the Tribunal limited both testimonies to the "technical and scientific aspects".

Cargill’s expert witnesses

Cargill had two expert witnesses, Dr Puah and Dr Nga. The Tribunal drew little from Dr Puah's evidence because he did not appear to possess the relevant expertise to assist the Tribunal in the hearing or to testify with confidence on the matters in question. In its decision, the Tribunal held that it treaded with "caution" in relying on Dr Nga’s evidence as he had admitted under cross-examination that his views were made with the benefit of hindsight.

The Tribunal concluded that the claims of the patent lacked inventive step and decided that Cargill succeeded in its application to revoke the patent. Martek filed an appeal against the decision of the Tribunal.

The Court’s decision

The Court held that as Dr Nga's evidence was based on hindsight, this was already fatal to his evidence as to the inventiveness of the patent. As the Tribunal did not rely on Dr Pauh’s evidence in making its findings, Dr Pauh evidence was not relevant for the purposes of the appeal. The Tribunal therefore had no basis to conclude that the claims would have been obvious to a skilled reader.

With regard to the testimonies of Dr Barclay and Dr Kyle, the Court agreed with the Tribunal that this is one of those cases with a high degree of specificity and expertise in the technology involved and where it is therefore not surprising if only a limited number of experts are available, such that pre-eminent experts may have certain work experience which might at first sight appear to threaten their independence.

The Court therefore relied on the testimonies of Dr Barclay and Dr Kyle, in that the claims did involve inventive steps. The Court held that even confining their evidence to the technical and scientific aspects of the Patent as such on the basis that they may be interested parties in respect of the Patent, the inventiveness of the Patent is one such technical and scientific aspect. The Court went further to say that Cargill failed to make out a case for actual bias and adduce their own expert evidence to disapprove the testimonies of Dr Barclay and Dr Kyle.

The Court therefore found that the Tribunal erred in finding that the independent claims lacked inventive step and allowed Martek’s appeal.

This article was written by:

Howard Yap
Patent Attorney 

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