The IPEC drills Claydon on disclosure of an invention by prior use

Case Reports

This decision tests the general principle of UK patent law that if an invention is ‘seen’ before filing any patent application, it cannot be patented. It also demonstrates just how important it is to take extra care when testing invention prototypes in (or near) public spaces.

If you would like to discuss this decision and how it relates to your own patent portfolio, please do not hesitate to contact someone from our patents team.

Background of the Decision

The two patents considered by the Intellectual Property Enterprise Court (“IPEC”) in this decision related to seed drills for sowing seeds in a field whereby there are two “tines” for slotting and seeding which are in alignment.

Novelty and Alleged Prior Use

One of the requirements for an invention to be entitled to patent protection is that it must be new. In order for an invention to be considered new under Section 2(2) of the UK’s Patents Act 1977, it must not form part of ‘the state of the art’, i.e. all matter which is available to the public anywhere in the world in any manner, before the effective filing date of the patent.

Mzuri alleged that the UK patent was invalid for not being new due to a disclosure by the inventor, Mr Claydon, on his farm. Mr Claydon tested the invention prototype in a field on his farm for ten hours over two days before filing for the patents. The field in question was surrounded by a six-feet tall hedge with several gaps through which Mzuri alleged that a member of the public could peep from an adjacent public footpath.

Under UK patent law, even if there is no one to observe a disclosure, just a possibility of prior public use being observed can deprive an invention of its novelty, and thus lead to the loss of patent protection. In other words, in the present case the question was not whether a person did see the testing on the field from the footpath, but what they could have seen had they been present on the public footpath.

In summarising the law, the judge in particular referred to decision E. Mishan & Sons Inc v Hozelock Ltd [2019] EWHC 991 (Pat). This decision considered whether the testing of an expandable hose by the inventor in his back garden constituted a public disclosure, as the garden was visible from a public road. In the end the question of disclosure came down to whether the inventor would have taken action to prevent an observer from viewing the invention should they have appeared. In Mishan, the judge considered that the inventor would have taken action, and so the hose was not disclosed. We previously reported on this decision here.

Applying these principles to the present case, Claydon argued that Mr Claydon had experience of patents at the time, and so would have moved away the seed drill (attached to his tractor) from any observer that happened to appear nearby on the public footpath to prevent them from seeing it.

The judge, however, was not convinced that there was anything Mr Claydon could have done to prevent a skilled observer from seeing the prototype should they have appeared on the footpath, and concluded that for this reason, the invention of the patent had been disclosed and was not new. The judge noted that hiding a seed drill prototype in a field is a good deal more difficult than hiding a prototype garden hose (as was the case in Mishan).

Even if an invention is observable, for it to be considered made publicly available the disclosure must be an enabling disclosure, i.e., must be one in which the public is given all information necessary to work the invention.

In the present case, there was an argument between the parties as to whether a skilled observer would be able to deduce that the two tines of the seed drill prototype were in alignment when standing on the public footpath. The judge considered they would be able to deduce this. In fact, the judge then went as far as stating that even if the tractor and seed drill prototype had been moved away from this hypothetical observer, as Mr Claydon said he would have done, the pattern in the soil left in the seed drills’ wake would have allowed them to deduce the alignment of the two tines anyway.

Obviousness and Infringement

For an invention to be entitled to patent protection it must also be inventive, i.e., not be obvious over the ‘state of the art’. This issue was also considered by the judge in view of various publications.

The judge held that Mzuri’s Pro-Til seed drills would have infringed one of Claydon’s patents if it had been found valid, but not the other.


Based on this judgment it is quite clear that if you have an invention and need to test it outdoors, it must be done in such a way that it is kept secret, and at least in a location where someone passing by could not observe it or, if they did, you would need to be able to show that they would not be able to deduce how it worked.

However, in general it is best practice not to test your prototypes outdoors or in a way that can be seen by the public.

The full judgment can be found here.

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