The Court of Appeal decision in E. Mishan & Sons Limited v Hozelock & Ors concerns that rare beast - a dispute over a simple mechanical patent which requires no specialist knowledge to understand. It is, though, an interesting and unusual decision in two respects. First, it concerns a patent which has previously been litigated and upheld, only for it to be held invalid, in a second action, over the same piece of prior art as considered in the first action. Secondly, notwithstanding the simplicity of the patent in question, and the fact that the legal principles involved are long-settled in English law, two very experienced patent judges, sitting in the Court of Appeal, have reached opposite conclusions on whether the patent is obvious over the prior art.
The patent claims expandable garden hoses, in which an expandable inner tube is housed within a non-elastic outer tube which ruffles when not in use. When connected to water pressure, the inner tube expands in size and unruffles the outer tube, which thereby increases in length. Hoses made to the patent are substantially smaller and lighter than traditional hoses, making storage easier and more convenient. The invention was made by an inventor in his garden and garage, and the product has been a significant commercial success.
In the first action, Blue Gentian LLC v Tristar Products (UK) Ltd, Birss J upheld the validity of the patent. It was common ground in this second action that he was right to do so on the evidence before him, as was confirmed by the Court of Appeal in the first action. Although the same piece of prior art was relied upon in the first action as in the second action, the expert evidence was substantially different. The prior art, McDonald, was a patent relating to an expandable oxygen hose for use in aircraft cabins. It works in the same way as the patent, but the fluid is a gas in McDonald, as opposed to water in the patent. Critically and unusually, neither party's expert in the first action had any experience in the design or manufacture of hoses, garden or otherwise. That had two consequences. First, the judge in the first action decided that the skilled person would be a designer of garden hoses, but would not have knowledge of other types of hoses (termed "technical hoses"), such as that taught in McDonald. Secondly, and consequentially, the skilled person would not, without the benefit of hindsight, think to apply the principle as disclosed in McDonald to garden hoses.
In the second action, the defendant's expert witness (but not the claimant's) did have considerable experience in designing both garden hoses and technical hoses. The Patents Court judge, Nugee J, held, contrary to Birss J in the first action, that the skilled person would be a hose designer with exposure to both garden and technical hoses. Such a designer would, clearly, more readily transfer an idea from the "technical hose" sector across to the garden hose sector than an person confined only to the garden hose sector. Given that McDonald teaches the same principle as in the patent, the only difference being the fluid passing through the hoses, the patent was held to be obvious over McDonald.
On appeal, the judges had to decide two issues. First, had Nugee J erred in his approach to assessing obviousness over McDonald by conducting a hindsight-based analysis? Secondly, had he erred when failing to take commercial success into account when assessing obviousness?
Arnold LJ, with whom Henderson LJ concurred, rejected both grounds of appeal. Looked at properly, the judge had not used hindsight, or at least no more than is permissible (as Arnold LJ explains at paragraph 76, a degree of hindsight is built into the European patent system's approach to obviousness). The judge was entitled to accept the defendant's expert's evidence that the skilled person would have translated an idea from one sector in which he worked across to another. In the absence of an error of principle, the Court of Appeal could not overturn that ruling. As for commercial success, Arnold LJ explained that this would only have been a relevant factor had McDonald actually been known to people within the hose industry. That is because, in such circumstances, the success would have provided an insight into the thinking of the skilled person when considering McDonald - the question would have been "if it was so obvious over McDonald, why wasn't it done before?". Where, as here, a piece of prior art was not known by people working within the relevant sector (McDonald had never been commercially produced), commercial success is simply irrelevant.
Floyd LJ, in the minority, agreed with the majority in relation to commercial success. However, he considered that Nugee J had erred in applying too much hindsight when considering McDonald. Floyd LJ was of the view that the nature of McDonald - a "paper proposal" which had never been implemented - was a relevant factor to take into account. Specifically, the fact that it had never been implemented ought to have raised scepticism in the judge's eyes as to its interest to the skilled person.
In the author's view, the approach of the majority is to be preferred. The same argument as in relation to commercial success applies - if McDonald had been known within the hose industry, the fact that no-one had ever bothered to implement it could have been a relevant factor as to its likely interest to the skilled person. Where, as here, McDonald was not known, its lack of implementation is irrelevant, and the judge was entitled to find that the skilled person would read it with interest.
In the author's view, there are two "take home" messages from the decision. The first is that whereas the patent system can protect simple mechanical inventions, such patents are potentially vulnerable to attack from prior art from other fields which was not known (and in all likelihood would probably not have been identified by a real-world search) in the field of the patent at the filing date. The second is that the choice of expert witness is absolutely critical in patent litigation. The role of the experts is primarily to educate the judge. Where, as in the first action, the experts do not have sufficient relevant practical experience in the sector of the patent to assist the judge, the judge may decide the attributes of the skilled person in too narrow (or, potentially, too wide) a manner. That is inevitable, because no judge can be expected to know such sector-specific information without the experts' help. The attributes of the skilled person can have a dramatic knock-on effect when it comes to considering the prior art, particularly where the prior art relied upon is from a different field, as in this instance.
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