Patents: invalidity due to prior public use

Background

A patent may only be granted for an invention which is new (section 1, Patents Act 1977). An invention is new if it does not form part of the state of the art. The state of the art comprises everything made available to the public by means of a written or oral description, by use, or in any other way, before the date of filing of a patent application.

The mere potential for prior public use to have been observed can deprive an invention of novelty and so disclosures in a publicly visible place may be prior art even if no one was there to observe the disclosure.

In Mishan & Sons Inc v Hozelock Ltd, the Patents Court held that a series of tests of the patented hose by the inventor in his garden did not constitute prior use, even though the tests would have been visible from the public road, because the invention would only have been disclosed to a skilled person watching from the road by putting together a mosaic of the various tests carried out by the inventor, and this was not what the skilled person would have done ([2019] EWHC 991 (Pat)). The inventor's evidence was that he would have immediately packed up and gone inside if he had seen anyone watching.

Facts

The inventor, C, of the seed drill tested a prototype of his invention in a field on his own farm before the patent application was filed.

M argued that the prototype in the field could have been observed from a public footpath. The footpath 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, although there were three gaps in the hedge through which the field could be seen by an observer.

C argued that he was aware that prior public use of his invention could jeopardise his ability to obtain patent protection. From the vantage point of his tractor cab, if he had seen someone on the footpath when he was testing the prototype, C argued that he would have manoeuvred the tractor so that the drill prototype was not visible.

Decision

The IPEC held that the patent lacked novelty because of the prior public use.

The field trial of the seed drill was a prior use of the invention which invalidated the patent, even though no member of the public had observed that use. The trial would have been observable from a public footpath, and, if there had been a skilled person observing the trial, they would have been able to gather enough information for this to be an enabling disclosure.

In Hozelock, the observer would not have been able to see all the elements of the invention needed for enablement, whereas here a skilled observer would have been able to do so, as large pieces of agricultural machinery are not as easy to hide as garden hoses.

Although not relevant here, the IPEC considered there is no absolute bar in law to the enablement of an invention by reason of the hypothetical skilled person having gained an understanding of it with the assistance of technical equipment. The evidence here did not sufficiently explore what equipment a member of the public might reasonably have been expected to carry and use to observe C's prototype without being in breach of an implied obligation of confidence. Nor did it explore what could have been discerned in the prevailing conditions using binoculars or a video camera typically available at the filing date of the patent application in 2002. It followed that, in this case, enablement must be assessed by reference to what could have been seen with the naked eye.

Comment

The IPEC raised but did not answer the question of whether a potential observer could have access to technical equipment, and cited two examples in a contemporary context. If enablement requires a phone with a sufficient zoom facility and the evidence shows that at the relevant time and place a member of the public could reasonably have been expected to carry a phone and use the zoom and could have done so lawfully, then it may be that the hypothesis will go forward on the basis that the information made available includes information obtained using the phone, whether seen at the time or recorded and discerned later. On the other hand, the evidence will not often establish a skilled person to have access to a drone swarm at the relevant time and place and, even if they did, use of the swarm may give rise to issues of privacy and breach of confidence.

The mere potential for prior public use to have been observed, even if it was in fact unobserved, can lead to the surprising and arguably unfair invalidation of a patent. The IPEC’s comments about assistance from technical equipment may point the way to a more nuanced assessment of the potential for disclosure of the invention to a skilled person.

Case: Claydon Yield-O-Meter v Mzuri [2021] EWHC 1007 (IPEC).

*First published in the June issue of PLC Magazine and reproduced with the kind permission of the publishers. Subscription enquiries 020 7202 1200