IP-Fälle und Artikel

When Should a Patent Application be Filed?

It is rare that an invention is fully developed at that all important “Eureka!” moment. Indeed, Edison is believed to have said, “invention is 1% inspiration, 99% perspiration”. Further investigation and development of the invention is almost always required to ensure that it works properly. This process of development and refinement leads on to the question: “When should I first file a patent application for my invention?”

The answer to this, unfortunately, is not simple. However, with an understanding of the effects of a 'filing date', an informed decision can be made.

Filing date

In most countries (but notably not the United States), the patent system functions on what is called a 'first to file' basis. This means that the date at which a valid patent application for an invention is received at a patent office is the date against which it is assessed for novelty and obviousness. Thus, any information publicly available before the filing date is used to assess whether the invention is new and not obvious.

Given this, it is extremely important to ensure that time is not wasted before filing a patent application.


The importance of obtaining an early filing date is countered by the requirement for the invention to be sufficiently disclosed. This means that, at the filing date, a person skilled in the art must be able to reproduce the invention using only their common general knowledge and the information available in the patent application.

If a patent application is filed which fails to teach how to reproduce the invention, or the notional skilled person would have to embark on undue experimentation in order to reproduce the invention, then the sufficiency requirement is not satisfied.

The level of information needed in a patent application will vary depending on the technical field in question. In some cases, once the invention has been proposed, its reproduction would be simple and would not require extensive exemplification. Indeed, a prototype of the invention may not even necessarily be produced, provided that the skilled person is easily able to produce the invention using the general information in the patent application. On the other hand, where an invention is complex, prototypes and examples are important in explaining how the invention works.

Of course, it is always recommended that at least one example of the invention is included. Also, because patent claims are often drafted to be slightly broader than the very specific commercial product, it is important that the patent application contains examples which support the claim across its entire breadth: just as a large roof needs numerous supporting beams which are evenly distributed, a broad claim should have numerous examples which are distributed evenly and not just concentrated in one area of the claim.

Industrial applicability

In addition to the sufficiency requirement, the patent application must also set out the industrial application of the invention in question. This is often immediately apparent where an invention has been devised in response to a specific problem. It may be an issue, however, where the invention has been devised following general research in a particular area.

For example, if a composition is devised which has surprising properties, yet no practical application of the composition is apparent, it is arguable whether the invention has any industrial application. That is not to say that the invention will not be found to be useful in some industry in the future, but at the date of filing, the industrial application of the invention was unclear. In this situation, it is generally not thought to be acceptable, at least in the United Kingdom, to speculate in the patent application as to the possible uses of an invention. Instead, an industrial application of the “invention” should be found before a patent application is filed. This issue has been the subject of debate in the UK courts in the field of biotechnology, where it was argued that patent applications were filed before an industrial application for the invention had been reliably proposed.

When to file

In summary, a first patent application should be filed when it is possible to explain to the skilled person how to reproduce the invention and the skilled person would only need their common general knowledge to do so. The industrial application of the invention should also be apparent.

Where the invention involves the application of a broad concept, the application should preferably be filed when sufficient examples which fully support this concept have been produced. Where the invention involves more specific subject matter, then it may be that an application can be filed when relatively few examples have been produced. In the case of a simple invention, which is very narrowly claimed, it may be sufficient to simply explain how to reproduce the invention, without the inclusion of a specific example of reference to a prototype.

If necessary, the first patent application can be treated as a 'priority' application. In this way, it is possible to utilise a 12-month period from the date of filing the first application in which to further develop and exemplify the invention. However, this 12-month period can not be relied upon in order to produce the necessary examples to enable the invention to be reproduced; the date for deciding when the invention is sufficiently disclosed is the filing date of the first application.