It is crucial to keep your invention secret until an application has been submitted to the patent office. Therefore, careful consideration needs to be given to testing or demonstrating any prospective inventions in public.
For various reasons, some inventions benefit from being investigated or demonstrated within view of the public. It could be that their size makes it impossible to keep them concealed (such as inventions on the scale of a wind turbine – see our previous articles on this area) or it could be that their inventive nature is only appreciated when utilised in a public setting. Ideally, a patent application is filed before this testing or demonstration takes place. However, there will be times when this may not be possible. For example, the success of the invention may only be realised following actual testing of various implementations.
The problem with putting your invention in public view ahead of submitting an application is that the public disclosure can stop you obtaining a valid patent. The amount of information that has been made available to the public, and thus how detrimental it is to the prospects of a patent, depends on exactly what was done.
If your product was freely put into the possession of a member of the public, such as by commercially selling it, then the European Patent Office considers all information that could have been discovered and reproduced by analysing the product to be part of the public knowledge. This is regardless of whether such analysis was actually conducted by anyone and regardless of whether there was actually any reason for performing this analysis. This could stop you obtaining a valid patent to an invention even if the patent is focused on the composition or internal structure of the product, which cannot be appreciated from its external appearance.
An analogous approach was utilised by the UK court in Lux Traffic Controls Limited v Pike Signals Ltd, where the ability of contractors to freely investigate a prototype traffic light control system meant that all the details of the invention were considered disclosed to the public regardless of what the actual contractors had learnt about the system.
In situations where the public can only see the product but do not have possession of it, the information will usually be limited to that gained from the examination of the product that was possible. This was the situation in the UK case of Wagner International v Earlex that related to a sprayer device that was demonstrated at a trade show and the EPO case T 1410/14 where a coupling of a vehicle could only have been observed overhead from a bridge as the vehicle travelled through the town. This shows that it is possible to keep some ‘hidden’ aspects of the invention a secret by controlling how much investigation the public can conduct of your product. It should be noted that a demonstration could be considered a public disclosure of the appearance of your product even if no one actually observed it. The logic behind this is that the opportunity for someone to have seen the demonstration is enough to make it a public disclosure. This is analogous to the approach normally adopted for a book in the library, which can be considered to be part of the public knowledge regardless of whether it has actually been read by anyone.
If your invention requires testing outside where a hypothetical member of the public could see it, a UK High Court judgment has concluded that it is possible to make sure it does not become public knowledge, but you have to take steps to make sure no one actually sees the invention. In Mishan v Hozelock, the inventor was conducting experiments on his inventive garden hose in his garden. This would have been seen by any member of the public that was on the road outside his house. However, the fact that the inventor would have seen if someone was watching and then would have packed up his invention to remove it from public view meant that no information about the hose was made public knowledge. It was important in this decision that the inventor’s mentality was to ensure the invention was kept a secret and so he would have acted accordingly. It is unlikely to be enough to avoid a public disclosure if it was just incidental that no one saw the inventor testing the invention.
Overall, by keeping some degree of control over the acts that are performed in public it is possible to limit the amount of information that publicly becomes available and so the amount of information that will be capable of adversely affecting any subsequent patent application. However, all of this is no substitute for filing an application ahead of any public disclosure of the invention whenever possible.
 Guidelines for Examination in the EPO, Part G-IV, 7.2.1
 EPO Enlarged Board of Appeal decision G 1/92