Practice and Procedure

Guidance on Expert Evidence

In Fisher & Paykel v Flexicare, Mr Justice Meade gave important guidance on how expert witnesses should be instructed in patent cases. The Court found that Fisher & Paykel's patent concerning the expiratory limbs of breathing circuits and in particular the use of breathable materials to reduce or eliminate condensation was valid.

The approach of the experts when preparing their respective reports had an impact on the Court's assessment of the obviousness attack. In particular, the Court concluded that Flexicare's expert had let in hindsight when preparing his written evidence, as well as when giving his oral evidence. 

The correct approach when instructing experts, specifically the sequence in which they are shown documents, has now been considered in a number of cases. The concern is that if an expert is shown the patent before they have assessed the common general knowledge or said what they consider to be obvious over the prior art, there is a risk of hindsight.

In Medimmune v Novartis, Arnold J said it was preferable for the expert to be asked about the common general knowledge, then shown the prior art, and only then shown the patent – so-called 'sequential unmasking'. However, Meade J noted that sequential unmasking can be a counsel of perfection. In particular, the expert may already be well aware what the invention of the patent is, e.g., from any commercial embodiment of the patentee. Here, the expert had prior knowledge of the patent's invention – whilst he had acknowledged this in his report, the Court concluded he should have thought carefully about this previous knowledge in order to avoid significant hindsight in his approach to a number of key questions.

In another decision from 2020, Akebia v Fibrogen, Arnold LJ noted that there was no rule or principle requiring sequential unmasking, and also acknowledged the practical problems that can arise, and also the extra burdens it can cause. He also stressed that lawyers instructing experts should not make the often arduous task of giving expert evidence even more difficult.

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Confidentiality Clubs

The Court of Appeal gave guidance in Mitsubishi v Oneplus as to the use of confidentiality clubs, in the context of a FRAND dispute where the relevant documents comprised comparable licences between the SEP owner and other licensees, some of whom the Defendants were also in negotiations with. The concern was that such information was highly sensitive commercially and "once learned, is not easily unlearned". This was in the context of an application to re-designate certain documents so as not to be limited to lawyers/experts, and also to include certain individuals of the Defendants in the confidentiality club.

In his judgment, Floyd LJ reviewed the authorities and distilled the following general principles relating to confidentiality clubs: 

1. In managing the disclosure of highly confidential information in IP litigation, the court must balance the interests of the receiving party in having the fullest possible access to relevant documents against the interests of the disclosing party, or third parties, in the preservation of their confidential commercial and technical information.
2. An arrangement under which an officer or employee of the receiving party gains no access at all to documents of importance at trial will be exceptionally rare, if indeed it can happen at all.
3. There is no universal form of order suitable for use in every case, or even at every stage of the same case.
4. The court must be alert to the fact that restricting disclosure to external eyes only at any stage is exceptional.
5. If an external eyes only tier is created for initial disclosure, the court should remember that the onus remains on the disclosing party throughout to justify that designation for the documents so designated.
6. Different types of information may require different degrees of protection, according to their value and potential for misuse. The protection to be afforded to a secret process may be greater than the protection to be afforded to commercial licences where the potential for misuse is less obvious.
7. Difficulties of policing misuse are also relevant.
8. The extent to which a party may be expected to contribute to the case based on a document is relevant.
9. The role which the documents will play in the action is also a material consideration.
10. The structure and organisation of the receiving party is a factor which feeds into the way the confidential information has to be handled.
11. The court must be alert to the misuse of the opportunity to designate documents as confidential. It remains the case that parties should not designate such material as attorneys' eyes only, even initially, unless they have satisfied themselves that there are solid grounds for establishing that restricting them in that way is necessary to protect their confidential content.
12. It is obvious from the above that the exercise of deciding what measure of restriction is justified involves the first instance judge in a judgment of the kind which an appellate court will not interfere with “unless the judge took into account anything which he ought not to have taken into account or that he left out of account anything which he ought to have taken into account, or that he erred in principle … [or that he was] plainly wrong”.

The Patents Court also considered confidentiality clubs following a finding in 2019 that Anan Kasei's patent for an automotive catalyst was valid and infringed, when disclosure was sought for the enquiry into damages (Anan Kasei v Neo Chemicals).

The parties had agreed to a confidentiality club regarding certain of Anan Kasei's documents which it claimed were confidential. However, they disagreed on the members of that club. Anan Kasei agreed to allow Neo's lawyers and experts to see the confidential information but not Neo's employees. Neo successfully applied to have its COO added to the club. Marcus Smith J held that it was necessary for the COO to be in the club as he was providing instructions and could consider any issues of settlement and was the primary interface in relation to the dispute. The COO was also a non-practising lawyer so understood the significance of the undertakings he was required to give.

Whilst Marcus Smith J considered the harm that may be caused to Anan Kasei by Neo's COO inadvertently (albeit innocently) using the confidential information, he held that the reasons for the COO to be in the club outweighed this risk. The judge also highlighted that, even where parties had consented to a club, the Court would carefully consider whether such protection was needed. He held that parties would also need to provide a "particularly clear and cogent justification" as to why a party should be excluded from a confidentiality club and that where a party contends that a particular person should be allowed in the club "the Court should be slow to second guess that contention".