Hacon HHJ and the Seed Drill: Intentionality in prior use (Claydon v Mzuri, [2021] EWHC 1007)

Does a tree falling in a forest make a sound? The answer to this epistemological cliché (and whether or not you care) depends on your philosophical leanings. Patent law has its own clear answer to the question. In UK patent law, the mere potential for prior public use to have been observed can deprive an invention of novelty. This principle can be a problem for inventors seeking to test prototypes of their inventions, and raises the question of how large, mechanical inventions can be tested without creating the potential (however small) for the invention to have been observed. The recent case of Claydon v Mzuri ([2021] EWHC 1007 (IPEC)) is a particularly harsh example of the application of the prior use case law. The patent was deprived of novelty in view of the inventor's prior use of a prototype of the invention (a seed drill) in a secluded field on his own land. 

Legal Background: Expandable hose pipes and the potentiality of disclosure

A general principle of UK patent case law is that disclosures in a publicly visible place are prior art even if no one was there to observe the disclosure. The classic example of such a disclosure is the unread PhD thesis languishing in a publicly accessible library. In Emson v Hozelock, Mr Justice Nugee (as then was), considered whether the development of a new garden hose by an inventor in his garden should be considered prior public use (IPKat: Mr Justice Nugee and the Superhose: The potentiality of disclosure). 

Audience of potential observers
In Emson v Hozelock the Judge was clearly conscious that categorising as "public disclosure" the private activities of an inventor in his garden, just because the garden was visible from the road, would not necessarily correspond to a common sense view of things. To rescue the situation, Mr Justice Nugee (as then was) focused on the effect of the inventor's intention on the potentiality of disclosure. In the case in question, the Judge observed that, if the inventor had seen anyone peering into his garden, he would have packed up the garden hose and gone inside. Thus, no potentiality of disclosure existed. 

By way of example, the Judge noted that a publicly advertised talk to which no-one turned up, but which nonetheless went ahead, would be public disclosure. However, an inventor talking to themselves on a deserted moor would not be public disclosure. The Judge reasoned that the soliloquising inventor on the moor could have been expected to stop speaking if they happened to have noticed someone walking behind them. 

To this Kat, the High Court's reasoning in Emson v Hozelock had its problems. Surely there would still be the potential for disclosure by the inventor hiking on the moors to a very soft-footed hiker creeping up behind them? Similarly, what if the inventor of the garden hose in Emson v Hozelock had been too wrapped up in his inventive activities to notice any observers?

You might think the field is empty

The question of when a prior use should be categorised as a public disclosure was again considered in the recent case of Claydon v MzuriThe case related to the alleged prior public use of a new seed drill. The alleged infringers and defendants, farm equipment suppliers Mzuri, argued that Claydon's UK patent claiming the invention (GB 2400296) were invalid in view of a prior public use by the inventor, Mr Claydon. 

The inventor of the seed drill tested a prototype of the invention in a field on his own farm before the patent application was filed. This fact was not in dispute. The question before the Judge was whether this prior use constituted public disclosure of the invention, given the potential for a skilled person to have observed the prototype seed drill. 

Mzuri argued that the prototype in the field could have been observed from a public footpath. The footpath in question was on the edge of the field, and was unmarked and unmaintained. There was a six foot high hedge between the footpath and the field. Crucially however, there were three gaps in the hedge through which the field could be seen by an intrepid countryside rambler. 

Mr Claydon argued that he was aware that prior public use of his invention could jeopardize his ability to get patent protection. He also had a good vantage point from his tractor cab. If he had seen someone on the footpath when he was testing the prototype, Mr Claydon submitted, he would have manoeuvred the tractor so that the drill prototype was not visible. 

Testing the prototype

Unfortunately for the patentee, the Judge, His Honour Judge Hacon (Hacon HHJ), was not convinced that Mr Clayton could have successfully hidden the large seed drill from a potential observer. As the Judge noted, large pieces of agricultural machinery are not as easy to hide as garden hoses. On the basis of expert witness testimony, the Judge also concluded that a hypothetical skilled person would have been able to deduce all of the claimed features of the invention from their vantage point at the edge of the field (para. 101). 

For Hacon HHJ, there had thus existed the clear potential for disclosure of the invention to a skilled person. The patent was thus found to lack novelty in view of the prior public use. 

The potentiality rabbit-hole

To this Kat, the outcome of this decision raises the question of the suitability of the potentiality of disclosure test for prior use. The patentee was deprived of their patent because the inventor had tested, unobserved, a prototype of his invention on his own land, just because there had been the potential (how every small) for a skilled person to look through a gap in the hedge from an overgrown and unmarked footpath. This does not feel like a wholly fair outcome. Indeed, despite his final decision, Hacon HHJ himself was obviously sympathetic to the plight of the patentee: "Mr Claydon had to test his prototype, nobody saw any of the testing and I entirely understand why he believed that his invention was not publicly disclosed" (para. 102) [Merpel: Indeed, what was the inventor expected to do, test his seed drill indoors?]

The concept of "intentionality" in prior use was arguably introduced in Emson v Hozelock as a way to avoid outcomes of patent invalidity based on prior use that would seem obviously unfair to the layman (IPKat). However, the decision in Claydon v Mzuri now reveals the limitations of the intentionality argument, and particularly the difficulty of building a case around the intentions that inventors may or may not have had many years ago. Hacon HHJ noted that he found "it hard to believe that nearly 20 years later Mr Claydon could accurately say with any certainty what he would have done" at the time the invention was conceived and tested (para. 92). 

Drone swarm

The Judge raised (but did not address) the question in Claydon v Mzuri of whether a potential observer could be afforded technical equipment in the form of binoculars, video recorder or even a swarm of drones (para. 80). The Judge steered away from the possibility of permitting most forms of skilled person the use of a drone swarm, believing that "it will not be often that evidence will establish" a skilled person to have access to a drone swarm at hand at the relevant time and place. Although, notably, the Judge doesn't completely rule this out. Nonetheless, discriminating between what (if any) technical equipment may be afforded a potential observer is a step away from the absolute principle that if a member of the public could have gained access to the invention (however unlikely), the invention should be considered disclosed. After all, there still remains the possibility for a member of the public to walk the fields of England with a drone or even a swarm of drones. 

It is thus perhaps in Hacon HHJ's reasoning on what technical equipment may be afforded to the skilled person that we find a possible escape from the "potentiality of disclosure" rabbit hole. Perhaps the answer is a more focussed assessment of the probability that a prior use could have been observed by a skilled person at a particular place at that time (e.g. more than negligible), as opposed to the existence of an absolute possibility, however small. 

Hacon HHJ and the Seed Drill: Intentionality in prior use (Claydon v Mzuri, [2021] EWHC 1007) Hacon HHJ and the Seed Drill: Intentionality in prior use (Claydon v Mzuri, [2021] EWHC 1007) Reviewed by Rose Hughes on Tuesday, April 27, 2021 Rating: 5


  1. Two thoughts (by someone not legally qualified)

    1. Would it matter if the novelty could not be determined by the hypothetical observer from his vantage point? For instance if the novelty related to having two types of seed planted alternately, the invention being the supply of seeds to the seed drill.
    2. S. 51 (30) of the Patents Act 1949 provided that:
    “An invention claimed in a complete specification shall not be deemed to have been anticipated by reason only that, at any time within one year before the priority date of the relevant claim of the specification, the invention was publicly worked in the United Kingdom…..if the working was effected for the purpose of reasonable trial only and if it was reasonably necessary, having regard to the nature of the invention, that the working for that purpose should be effected in public”. One wonders why such a provision was not continued in the 1977 Act.

    1. The question of enablement is certainly a relevant issue. However, in this case it looks like the judge found that a distant observer would understand how the invention worked simply from sight. The typical way this issue is approach in FC exam question is that 'a black box' is publicly disclosed, where the input and output are visible, but the workings unseen. Assuming that the 'invention' lies in the workings rather than the output itself, that would not be an enabling disclosure.

      Personally I prefer slimmed-down and simple legislation. The problem with provisions like s.51 of the '49 act to which you refer is the vaguety of terms like 'reasonable trial', 'reasonably necessary'. Things like that introduce a great deal of uncertainty into a legal determination. That could well consume whole days of pre-action DD and trail argueing about reasonableness. And I think often that degree of uncertainty will itself practically deprive a small patentee, e.g., an SME or private inventor, from enforcing patent rights.

    2. To xxxxxxxx 27 April, the answer to your question about the incorporation of the provision from the 1949 Act in the 1977 Act is that the relevant sections of the 77 Act are framed to harmonise with the EPC, which has no such provisions.

      One thing that struck me while reading this thread and skimming through the decision itself is that the prior user was supposed to have taken place around 20 years ago. How did it come to light in this litigation?

  2. Proponents for a grace period will certainly wake up!

    I understand the way the judge argued, but I find the result deeply unfair for the proprietor.

    1. Yes, indeed, a grace period. More trouble than it's worth, is my initial reaction, like the observations of the commenter below on reinstating a test of "reasonableness" on pre-filing trials.

      Fact is though, some farmers are very inventive and come up with commercially very valuable improvements in farm machinery. But soil being what it is (infinitely variable) who knows whether a paper proposal will work without first testing it out with a day's work on real soil? It is "unreasonable" to expect every paper proposal to be exhaustively described, claimed and deposited at the Patent Office, even before a first trial on real soil. And it is unreasonable to expect elaborate screens and shrouds to be placed over and around the machine before driving it out of the isolated workshop and into the remote field outside, just in case some oik with a drone and a camera could theoretically have been larking around, in the vicinity, at just the right moment. Come on English patent judges, you can do better than this.

  3. Scanning through the patent claims, some of the dependent claims appear to be difficult to detect from afar. However, in the judgment, only infringement of claim 16 as dependent on claim 8 was alleged. Claim 16 seems possible to detect from a distance, and it was interpreted quite broadly which didn't help (para 99). Therefore, Claydon seems unlucky in relation to which dependent claims were infringed.

    Another factor appears to be the alleged unreliability of the witness statements (para 92).

    This somewhat distinguishes from the Hozelock case in which the prototype testing process was well documented on video, and where the features in the infringed claims were not seen as obvious to a nearby observer.

    It still seems unfair, and nobody wants to see it become standard practice to dream up all kinds of hypothetical scenarios in which a member of public could have seen the invention.

  4. I am a patent attorney who grew up on a farm in The Midlands. I am unhappy about the finding of prior public use and write here to express my discomfort with the decision. The law does not concern itself with trifles, it disregards de minimis facts and when it comes to novelty ought to give some respect to the EPO's established Gold Standard under which the claimed subject matter must be directly and unambiguously derivable from the prior disclosure or else novelty is not prejudiced. What is merely "obvious" to the observer does not "count" and is NOT what decides the issue..

    A disclosure in a factory, in a corner of a book-filled room, or on a public road is one thing. On an empty moor is another, as the decision notes. On that spectrum, where does the open expanse of arable land, relevant here, lie? Closer to that open moor, I say, than to the situations in the precedent cases.

    It seems to have been decisive that there was a public footpath in the vicinity of the machine trial. But the footpath was not popular, rarely used. Consider OS maps of the English countryside. They are littered with markings of old "Rights of Way" unused these days. Read Wainwright's Coast to Coast book, and see how the old master himself found it well nigh impossible to follow these markings on maps in fertile arable country. The likelihood of some member of the public walking that particular section of the disused footpath, just at the right moment, and on just the week-day of the trial (as opposed to a Sunday Afternoon), and having a chance to observe the trial, strikes me as so remote, so de minimis, as not to "count" as the basis of a prior "public" use.

    Further, there is the issue what the walker could have derived. The law of novelty ought to hold to its distinction between what is "obvious" from a disclosure and what could have been derived "unambiguously".

    I daresay, that a farm machinery expert, walking the footpath while the machine trial was happening, might have found obvious a lot of constructional details of the machine. But the idea that such a person would derive unambiguously the specific combination of technical features of the claim strikes me as fanciful. To the contrary, that curiosity of that person would have been highly aroused, precisely because i) the machine being operated was obviously interesting but ii) closer inspection would be felt imperative, because only then could the observer derive and grasp the key features of construction and operation of the curious machine.

    I agree with you, Rose, that the outcome seems unfair. That's because it is unfair. A poor show, I would say. Patent law should accord with what those with a business interest in patent law accept as fair, or else the level of respect for the law is diminished.

  5. Mind boggling. This area of prior use needs to change.

  6. This case is in some ways similar to the Unwired Planet case ([2015] EWHC 3366 (Pat) ). There, a disclosure to the standard setting organization the 8th January was available in Hawaii on 7th January, one day before the filing of the priority application. Birss J. (as he then was) came to the conclusion that this disclosure to the SSO was not relevant for considering patentability.
    If a member of the public had access to the disclosure before the filing date, normally this would be considered a relevant disclosure but the judge presumably thought this would not be fair to the applicant.
    In this case, the judge does not seem to have considered "fairness" to the applicant.
    The statute uses the language "made avaialble to the public" yet in the trials there was no intention to make the invention public, distinguishing from the thesis in a library example where the publication is intended.
    Hopefully, an appeal will be filed.

  7. This case gets more and more strange, once you start comparing the patent specification with the prior art machine of the Handy US patent. The court found that Handy did not prejudice the validity of the claims. But it looks an awful lot like the claimed machine. If i were that mythical beast observing from the footpath, I should not be able to see whether the machine in the field was a Handy machine or a Claydon machine. Has Claydon made his machine 2available"? i suspect not.

    But now let's look at how the leading tine of Handy operates and how the lead tine operates in Claydon. For the court, they operate differently. but it seems to me that they are not different.

    See Claydon, the patent in suit, Figs 7 and 8, reference 106. according to the sentence bridging pages 14 and 15 of the GB B publication, that triangular mass of soil is "broken up" by the "slotter tines" 104. Soil is like that. It is friable. Tines advancing through it break it up. It is not to be confused with the progress of a knife through butter.

    Now look at para 117 of the Decision, second sentence. I think that conclusion by the judge must be wrong. I think Handy's lead tine, advancing through the same material, soil, works that soil just like Claydon's slotter tine.



  8. The mind boggles. Surely the judiciary must ask themselves what they want the future precedent to be when they make these decisions, and consider any impact? Surely the purpose of the patent system is to encourage research and development of new technologies? And yet here we are told that research is disclosure for anything that can't be tested indoors, more or less. Baffling.

  9. Comparison with the opposition to the EP family member (1608214) is interesting. The EP-B was revoked for obviousness and to get there the Board used the same prior publication (Handy) as in the English court. The difference was that the Board combined Handy with another prior-published US patent specification whereas the court in England needed x-exam of the rival experts in soil cultivation to establish the cgk.

    One speaks of "The blind leading the blind". Reading the Decision, my sense is that in this case the x-exam process was toe-curling for the respective clients, infuriating for the rival experts, and frustrating for the judge. My hunch is that the barristers lacked any "feel" for the way soil reacts to tines being pulled at pace (as the saying goes) through it by a powerful tractor that brooks no resistance to its progress, and so failed to elicit clear and concise answers from the experts. I suspect the x-exam process left the respective experts deeply sceptical of an English court's techniques for resolving an issue of fact.

    Which is a great pity because the huge costs of going to trial in England can be justified only by England's supposedly far superior forensic fact-finding procedures. I suppose that these procedures work best when the client leaves the litigation team free from any budgetary considerations, free to win the case "whatever it takes". I see that this case was fought out in the IP Enterprise Court, not the High Court. Hmmmm!

    At the EPO, Boards of Appeal are not encumbered by such fact-finding processes, nor by any doctrine of Binding Precedent. One might therefore suppose that the Boards are less likely to get to a result that can be respected. But, hey, read the EPO Decision and decide for yourselves, dear Readers.


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