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UK – Blue Gentian Llc & Anor v Tristar Products

15 Jan 2014

Blue Gentian Llc & Anor v Tristar Products (UK) Ltd & Anor, Patents Court (Birss J), London, UK, Case No. [2013] EWHC 4098 (Pat)

In its judgment of 20 December 2013 the High Court of England and Wales decided a case regarding expandable garden water hoses. The trial was expedited, resulting in a speedy (and relatively brief) judgment less than five months after issuance of the claim form (and less than 18 months after the patent was filed). The case demonstrates that appropriate patent cases can be decided very quickly in the English High Court.

The judgment is of general interest in relation to the instruction of expert witnesses. The court held that the fact that the defendant’s expert was aware of the patented invention before he considered the prior art did not necessarily mean his views were tainted by hindsight. Other recent cases have emphasised the importance of presenting experts with the patent after the prior art (e.g. see here at [5]). However, this judgment reflects the reality that certain experts may be aware of particular inventions before the relevant patent is presented to them.

The case also deals with issues that arise where prior art comes from a different field compared to the patent. The court held that “at least” in relation to novelty, prior art must be assessed by the person to whom it was addressed. However, in relation to obviousness, the parties agreed that this must be assessed by the person to whom the patent-in-suit is addressed, and the court proceeded on that basis. In such cases expert evidence from both fields may be helpful. However, this case illustrates the difficulties in mounting a successful obviousness attack based on prior art in a different field.


By the trial the issues had been narrowed to the validity of two claims: one product (a hose) and one method (of transporting water). The defendant accepted both would be infringed if valid. The defendant relied on two items of prior art: ‘McDonald’ and ‘Ragner’ (both US patent applications).

A dispute regarding claim construction arose because McDonald describes an oxygen hose used for air crew in an aircraft. The defendant argued that the claim for “a garden water hose assembly” should be interpreted by reference to its objective characteristics (i.e. suitable for use as a garden hose). The court accepted that objectivity was key; however, the ambit and scope of the claim had to be determined in a “realistic and fair” way (e.g. a hypothetical hose with tiny diameter and length of only 10cm would not be a ‘garden hose assembly’).

Prior art item 1: Ragner
Ragner describes expandable/retractable hoses featuring springs. However, it also contemplates using the hose cover as the “biasing mechanism” (i.e. to extend the hose) instead of a spring.
The court rejected the defendant’s novelty arguments as Ragner did not disclose the particular combination claimed in the patent-in-suit. Nor was the invention an inevitable result of the disclosure in Ragner.

Of general interest are the judge’s comments on hindsight. During cross-examination the defendant’s expert (Mr Howe) accepted that he had been aware of the patented invention before he considered the prior art. The claimant argued that Mr Howe’s evidence was tainted with hindsight and that because their expert (Mr Sinclair) had been presented with the prior art before seeing the patent his opinion on obviousness should be preferred over Mr Howe’s. The court rejected this argument, seeing “no value in the difference” between the experts’ instructions.

The court proceeded to find the patent inventive over Ragner on the basis that while each step may in hindsight seem obvious, invention lay in perceiving that the final result was attainable from the starting point) and linking the various elements.

Prior art item 2: McDonald
McDonald describes a way of providing oxygen to crew on an aircraft using a mask attached to a hose.
McDonald was clearly not addressed to the skilled addressee of the patent-in-suit (a garden water hose designer). However, the court held that the fact that a garden water hose designer might not fully understand McDonald does not reduce its contribution to the art. The court held that, “at least” in relation to novelty, McDonald’s contribution had to be assessed by the person to whom it was addressed (i.e. a manufacturer of equipment for aircraft). On the other hand the parties agreed that obviousness had to be assessed by a garden water hose designer, and the court approached the matter in that way.
Absent evidence from a manufacturer of equipment for aircraft, the court considered the experts’ views on the interpretation of McDonald. The court held that the invention in McDonald was supposed to work in a way similar to that in the patent-in-suit and involved a similar combination of elements. The claimant argued, and the court accepted, that McDonald was not explained clearly and might well not be practical. However, the court did not accept that McDonald lacked any enabling disclosure. The court proceeded to find that McDonald disclosed almost all the features of the product claim in the patent-in-suit. However, the court held that McDonald did not anticipate the “garden water hose assembly” requirement, primarily because the necessary expansion depended upon the face mask and a hose with a mask is not suitable for use as a garden hose. Accordingly, the patent-in-suit was novel over McDonald.

In relation to obviousness, the claimant argued that a garden water hose designer would not understand how McDonald achieved its claimed result and would be concerned that it might not be practical as a garden water hose. A garden water hose designer would discard McDonald because they would not consider it suitable for use as a garden water hose and there would be no incentive or obvious benefit to modify it. The court accepted that it would not be immediately apparent to a garden water hose designer that McDonald was suitable for use as a garden water hose or that this would be practical. Accordingly, the patent-in-suit was inventive over McDonald.

Finally, the claimant quoted a UKIPO opinion suggesting that McDonald was not prior art and should not be considered in relation to obviousness. The court disagreed, but the patent was upheld in any event.
Read the decision (in English) here.

Head note: Scott Parker and William Corbett