Blue Gentian LLC & Anor v Tristar Products (UK) Ltd & Anor

In an appeal on patent obviousness, the Court of Appeal should not interfere with a trial judge’s multifactorial assessment unless there is an error of principle. Obviousness must be assessed without hindsight, particularly where the invention provides substantial practical advantages. A prior-art document directed to a different technical field does not make an invention obvious merely because a skilled person could adapt it. The question is whether the skilled but unimaginative person would have had a reasonable expectation that the adaptation would work, having regard to the document’s teaching, missing technical details and practical context. A suggestion that one component may perform a function does not necessarily make obvious the claimed combination of components, especially where their interaction and relative movement are central to the invention.

Blue Gentian sued Tristar for infringement of a patent concerning an expandable garden water hose. Tristar accepted that its activities fell within claim 1 and claim 14, but contended that the patent was invalid for lack of novelty or obviousness in light of the Ragner and McDonald patent applications. Birss J rejected the validity attacks and found infringement in [2013] EWHC 4098 (Pat).

On appeal, Tristar challenged only the obviousness findings. It argued that the judge had misconstrued Ragner and McDonald and had relied improperly on expert evidence. The central issue was whether either publication made the claimed garden hose obvious to the skilled person, or whether the judge had made an error of principle.

Disposition

Lord Justice Kitchin delivered the leading judgment. Lord Justice Tomlinson and Lady Justice Hallett agreed. The appeal was dismissed.

1. Appellate review. Obviousness is a multifactorial evaluation, described as a kind of jury question. An appellate court should be reluctant to interfere with the trial judge’s assessment unless the judge has erred in principle. The Court found no such error.
2. Ragner. Ragner’s central teaching concerned a spring-based extendable and retractable hose. The spring operated not only as a biasing means but also as a support structure for the cover material, including by restraining excessive radial expansion. Although Ragner contemplated that cover material might provide some or all of the biasing force, it did not explain how such a design should be implemented or disclose a non-elastic outer cover in that context. The judge was entitled to conclude that, without the spring, Ragner gave no reason to retain the outer cover for the different function of constraining an elastic inner tube.
3. Ragner also did not make obvious the claimed arrangement in which the inner and outer tubes were connected only at their ends and could move freely relative to each other. The structure shown in Ragner had the covers moving together with the spring. Treating its separate disclosures as pointing to the patented combination would involve hindsight.
4. McDonald. McDonald concerned an aircraft oxygen hose comprising an inflatable elastomeric inner tube and an outer woven or braided sheath. Although the judge found that such a hose would operate under domestic water pressure, he was entitled to find that this would not have been apparent to an ordinary garden-hose designer. The designer would lack relevant knowledge about the aircraft mask, regulator, pressure and flow rate, and would view the document as addressing a distant technical environment. The document’s practical operation and deployment were insufficiently explained to create a reasonable expectation of success.
5. The fact that a skilled person could arrive at a product within the claim did not establish obviousness. The skilled but unimaginative person had to be assessed without hindsight, and the judge’s conclusions were supported by the evidence.

1. Court of Appeal (Civil Division): Appeal dismissed. The court upheld the obviousness findings and the consequential order.
2. High Court of Justice, Chancery Division (Patents Court): Birss J found infringement and rejected the challenges to validity in [2013] EWHC 4098 (Pat).