E Mishan & Sons, Inc v Hozelock Ltd & Ors

In an appeal on obviousness, the Court of Appeal must not substitute its own evaluation for that of the trial judge. Intervention requires an error of law or principle, or a conclusion not open on the evidence.

The notional skilled person is deemed to have read any pleaded prior art, however obscure, but approaches it without preconceptions that it is relevant. A remote document may nevertheless be an obvious starting point where its transferable teaching would be recognised. A single adaptation from a pressure-expandable aircraft oxygen hose to a garden water hose was open to the judge and did not involve hindsight.

Commercial success has weight only if it illuminates the skilled person's response to the particular prior art. Appeal dismissed.

Emson, the exclusive licensee of two expandable garden-hose patents, appealed from Nugee J's decision revoking the patents for obviousness over McDonald, a patent application for a self-elongating oxygen hose used with aircraft crew masks: [2019] EWHC 991 (Pat).

The judge had also found that the patents had the claimed priority date, survived alleged prior uses, and would have been infringed by Hozelock if valid. Hozelock challenged those findings by respondent's notice. The appeal concerned whether the obviousness assessment involved hindsight and whether the patents' commercial success assisted Emson. The respondent's notice was not reached because the appeal was dismissed.

Appeal dismissed by a majority. Arnold LJ gave the leading judgment and Henderson LJ agreed. Floyd LJ dissented.

1. Appellate restraint. Obviousness is a multi-factorial evaluative question. Applying the principle in Actavis Group PTC EHF v ICOS Corp [2019] UKSC 15, the court could intervene only for an error of law or principle, or where the conclusion was not open on the evidence.
2. Structured obviousness analysis. Nugee J correctly followed the Pozzoli structured approach: identifying the skilled person and common general knowledge, the inventive concept, the differences from the prior art, and whether those differences would have been obvious without knowledge of the invention.
3. McDonald and hindsight. McDonald disclosed a self-elongating hose with an inflatable elastomeric inner tube, a constraining woven or braided sheath, relaxed and expanded states, and pressure-actuated axial expansion. The judge was entitled to find that a hose designer exposed to garden and technical hoses would recognise that the principle was transferable from gases to water. The absence of disclosed diameters, gas pressures, flow-initiation details and retraction details did not make the teaching too confusing. The difference was a single adaptation to a garden hose, including water pressure and a flow restrictor, rather than a series of apparently easy steps. The judge's comparison of McDonald with the claimed invention at the third Pozzoli stage was not the statutory obviousness test and did not establish hindsight.
4. Other benefits and commercial success. Once obviousness was established for one reason, other non-obvious benefits did not alter the conclusion. Commercial success could assist only if it illuminated how the skilled person would have approached the particular prior art. McDonald was not shown to have been known in the hose industry, so the success of Xhose could not logically establish non-obviousness over it. Emson bore the burden of establishing that factual foundation.
5. Uncommercialised prior art. The lack of commercialisation was relevant but not decisive. Its weight depended on the age of the proposal, whether it had been disregarded or unused, and whether the evidence cast doubt on its teaching or applicability. McDonald was relatively recent, and there was no evidence that it failed to work. The judge's conclusion that the patents were obvious was therefore one with which the appellate court could not interfere.
6. Dissent. Floyd LJ considered that McDonald was a mere paper proposal which should have been approached with a high degree of scepticism. In his view, the judge assumed that it worked, failed to give proper weight to the long absence of innovation in garden-hose design, and treated shared space-saving objectives as sufficient without asking whether the skilled person would make the connection. He would have allowed the appeal.

It was unnecessary to decide Hozelock's respondent's notice; any observations on those issues would have been obiter.

• Court of Appeal (Civil Division): By a majority, dismissed Emson's appeal from the revocation of the patents for obviousness. Henderson LJ agreed with Arnold LJ; Floyd LJ would have allowed the appeal.
• High Court, Patents Court: Nugee J revoked GB 276 and EP 585 on the ground that the claims were obvious over McDonald: [2019] EWHC 991 (Pat).