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Earlier obscure 'paper proposal' invalidates hose patent

Posted on 23 July 2020

As a multi-factorial evaluation, the Court of Appeal rarely intervenes with a trial judge's assessment of whether a patented invention involves an inventive step, unless it identifies an error of principle or law. This includes those cases where the result may, as the Court accepted in Mishan v Hozelock, "appear harsh, even unfair" to the inventor.  Indeed, whilst there was an acknowledgement of a feeling that the inventor in this case should be able to "reap the rewards of his brilliantly simple invention", the wider public interest requires that patent protection should not be available where there is prior art either disclosing the invention or making it obvious, no matter how obscure.  

The decision is also noteworthy for the disagreement on the approach to take on a key issue between two highly experienced patent law judges: Arnold LJ, who was elevated to the Court of Appeal from the Patents Court last year, and Floyd LJ.    


Emson is the exclusive licensee of UK Patent No 2 490 276 and European Patent (UK) No 2 657 585 (the Patents) which relate to expandable garden hoses.  The hoses are compact when empty but expand in length when filled with water.  The commercial embodiment of the Patents, Xhose, has achieved considerable success.  Emson brought infringement proceedings against Hozelock's Superhoze product, and Hozelock challenged the validity of the Patents.   

At trial, there was an interesting analysis of arguments relating to prior use by the inventor (discussed here) but the Patents were revoked on the grounds that all the claims were obvious over an earlier US patent application called McDonald.  The McDonald application related to oxygen hoses to be used by cabin crew on an aircraft.  Whilst it did proceed to grant in the UK, and to a European Patent designating the UK, Germany and France, the invention claimed in McDonald was apparently never commercialised, and was therefore a 'mere paper proposal'.

Interestingly, in earlier proceedings with different defendants, one of the Patents had been found to be inventive over McDonald, albeit with materially different evidence before the Court (in that case, neither of the expert witnesses had experience in the design or manufacture of hoses).  The European Patent Office has also more recently rejected an argument of obviousness over the combination of a standard garden hose and McDonald in relation to the European Patent, albeit that decision is under appeal. 

Appeal on Obviousness

Applying the structured approach to the question of obviousness, the Judge had concluded that the differences between McDonald and the inventive concept claimed in the Patents were steps that would have been obvious to the skilled person in the art.  The Judge noted: "that may seem hard on Mr Berardi who is undoubtedly inventive … but if there is prior art, however obscure, which discloses either the same invention, or something which would lead the skilled person to the same invention, then patent protection is for good reasons unavailable".

Emson argued that the judge had applied an impermissible hindsight-based analysis in his assessment of inventive step.  However, giving the majority judgment, Arnold LJ noted that the trial judge had asked himself, correctly, whether the differences between McDonald and the inventive concept were steps which would have been obvious to the skilled person "viewed without any knowledge of the alleged invention as claimed" and had expressly stated that he did not consider his conclusion was based on hindsight.  He therefore was clearly conscious of the need to avoid hindsight.  Emson argued that certain statements made by the Judge betrayed hindsight reasoning but these arguments were unsuccessful.  The majority therefore concluded that the finding of obviousness was one that the trial Judge could properly make: McDonald unambiguously disclosed the same basic concept of an extendible and retractable hose as the invention claimed in the Patents.

However, Floyd LJ disagreed.  He highlighted the particular danger of hindsight when considering a simple invention such as this.  In his view, as a 'mere paper proposal', McDonald was less likely to render the invention obvious. In particular, unless the difference between the prior art and the invention was entirely trivial, he thought it was wrong to assume that a paper proposal could be successfully implemented when there was no evidence it had been over a substantial period.  To counter the argument that the document said it would work, he pointed out that any document describing apparatus would.  He therefore thought the Judge had treated a paper proposal as if it were something which had been made and tested, when the evidence of both experts was they could not fully understand the detail of how it was supposed to work.  For Floyd LJ, this was "redolent of the use of hindsight" and the Judge should have approached, with a high degree of scepticism, the suggestion that McDonald's disclosure would be regarded as useful by a skilled person interested in garden hose design.

Whilst Arnold LJ accepted that the lack of commercialisation was a relevant factor, the force of that consideration depended crucially on two factors:

  • If the prior art has been 'long disregarded', why was that the case?  The age of the prior art will be a relevant consideration but McDonald was only eight years old at the priority date of the Patents.  Further, it had not been 'disregarded', but was unknown to those in the hose industry.
  • If the prior art has been 'unused', again why was that the case? There was no evidence to suggest McDonald had not been commercialised because it did not work.

He also disagreed with Floyd LJ that the allegation of obviousness involved a step-by-step analysis of the kind that has previously been deprecated in the case law. In fact, it only required a single step to get from McDonald to the claimed invention.

Commercial success

Emson also argued that the Judge should have taken the commercial success of the Xhose into account when assessing obviousness.  It argued that the Xhose had been commercially successful because it had solved the problems with conventional hoses of being bulky, heavy and liable to kink, therefore meeting a long-felt want.  However, all of the Court of Appeal judges agreed with the trial judge that this argument would only be relevant if McDonald was known to the Xhose's designers – commercial success will only be a relevant factor where it provides an insight into the thinking of the skilled person when considering the prior art.


The judgment contains several statements of sympathy for the inventor in this case.  However, Arnold LJ stressed that, whilst the point of the patent system is to incentivise investment in, and disclosure of, innovation, patent law also contains a number of mechanisms to strike a balance with the competing public interest in competition.  Accordingly, "it inevitably follows that some patents turn out to be invalid because, unbeknownst to the inventor … prior art emerges when sufficient searches are carried out which anticipates or renders obvious the claimed invention". This was such a case.

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