Farrow Holdings Group Inc v Secretary of State for Defence

A patent claim requiring a fluid to be heated to a specified temperature range is concerned with the temperature of the fluid used in the process. It is not limited to fluid heated from below into that range, and may include fluid heated above it and subsequently cooled. Written evidence remains subject to critical evaluation even where the witness is not cross-examined. A tribunal may accept unchallenged evidence, but must weigh it against conflicting evidence and explain material conclusions. In assessing obviousness, a claimed temperature range may be obvious where the prior art teaches the use of hot fluid and the skilled person would select a practical range. An alleged technical prejudice requires cogent evidence of a widely held but incorrect technical belief. A claimed additional advantage may be no more than a bonus effect if the claimed method is otherwise obvious.

The Secretary of State applied to revoke two patents owned by Farrow Holdings Group Inc. The Hearing Officer, acting for the Comptroller, revoked both under section 72 of the Patents Act 1977 for lack of inventive step. On appeal, the patentee challenged only the decision concerning the parent patent, GB 2 344 348. The issues included alleged unfair pressure on the patentee’s litigant-in-person director, construction of the temperature limitation, assessment of evidence concerning prior use at Kalamaki, and obviousness over patent EP 0 358 648. The central questions were whether the prior use fell within the claim and whether the claimed temperature ranges involved an inventive step.

1. Article 6 ECHR. The Hearing Officer was entitled to indicate that the hearing might finish in one day because cross-examination was no longer required. He also properly invited counsel to accommodate the patentee’s litigant-in-person status. Viewed objectively and in context, the comments did not create unfair pressure. The fairness ground was dismissed.

2. Construction. The temperature limitation required the fluid used in the blasting process to be within the specified range. It did not prescribe the precise route by which that temperature was reached. Accordingly, water heated above the range and then allowed to cool into it could satisfy the claim.

3. Evidence. The absence of cross-examination did not oblige the Hearing Officer to accept written evidence. Evidence had to be critically assessed and weighed according to the evidence which each party could have produced or contradicted. The finding that the active-heating prior use occurred was nevertheless open to the Hearing Officer.

4. The Hearing Officer had not adequately explained why the passive-heating evidence was accepted despite expert evidence making it inherently unlikely that the water could reach 25°C within the relevant period. The court therefore reconsidered that issue and allowed the appeal concerning passive heating. The applicant had not established that variant sufficiently cogently.

5. The active-heating prior use nevertheless disclosed all relevant features apart from particle size, which was independently obvious. Claim 1 therefore remained invalid for lack of inventive step.

6. The prior patent taught the skilled person to use hot water to assist removal of oils and grease. Selecting a range hot enough to improve the process but not create a scalding risk was obvious. The alleged prejudice against hot water was not sufficiently proved, and evidence of commercial success did not alter the conclusion. The narrower 25–40°C range in claim 6 was also obvious; any reduction in water consumption was, at most, a bonus effect.

7. The appeal was dismissed overall.

• Comptroller of Patents: The Hearing Officer revoked both patents for lack of inventive step in decision BL O/353/13.
• High Court (Patents Court): The appeal concerning the parent patent was dismissed overall. The appeal was allowed on the evidential issue concerning passive heating, but the patent remained invalid on the basis of active heating and the prior patent.