Frequently Asked Questions: Determining the validity of patents

It is always possible to start a court procedure to annul a patent. However, this is expensive and complex. You have to demonstrate to the court that the patent does not meet the statutory requirements for patentability, for example because it is not novel or does not involve an inventive step. Proving this can be very difficult, even for supposedly trivial patents. You basically have to find prior art to support every statement you make about what would be trivial or obvious.

In Europe, when a European patent is granted, you can launch an opposition within the next nine months. This is a procedure before the EPO in Munich, in which you and the patent holder can discuss the patent's validity. The EPO opposition division and the EPO board of appeal are generally more technically qualified than judges in national courts, so it may be easier to convince them with technical arguments. However, an opposition is very unlikely to succeed without a professional representative (a European patent attorney) to help you.

Prior art is a term used in the patent world to indicate material that was publicly available before the "relevant date" of a patent or application. A patent must be novel and involve an inventive step (in the US: be non-obvious) when compared to the prior art. So, if you find a publication dated before the filing date of the patent, and that publication describes all aspects of the invention as claimed, the invention is not novel and the patent is invalid.

In most countries, the relevant date is the day of filing of the patent application. The USA, however, uses the date of invention to evaluate whether something is prior art or not (see also Differences between US and European patents).

If you find a publication that was publicly available before the relevant date, the next step is to compare the publication with the claims at the end of the patent document. You need to identify every single element mentioned in the independent claims in the publication. A claim is independent if it does not refer to another claim (usually in terms like "the device as claimed in claim 3" or "the device of claims 1-4"). If all elements of the independent claims are mentioned in the publication, you can then do the same with the dependent claims.

If all elements of the independent claims are mentioned in the publication, the subject matter of the independent claims is not novel. If at least one element is not mentioned, the independent claim is novel and may or may not be obvious.

For more information, see When is something prior art against a patent?.

Novelty is a patent term of art, and is very precisely defined. Patent documents contain a set of claims, which define the invention. The claims must define something that is novel (and not be obvious; see the next question). To determine if the claim does so, you must take a prior art document and try to find every element in the claim in that prior art document. If even a single element is not described in that document, the claimed invention is novel.

For example, a claim might say "A table having a round top and four legs protruding therefrom, the legs being evenly spaced around the circumference of the round top." If a prior art document describes a table with an elliptical top and four legs evenly spaced around the top, the claimed invention is novel, because elliptical is not the same as round. You could argue that it is almost the same, but that is a matter of obviousness, not novelty.

A patent is obvious if what is claimed is novel (see previous question), but the novel aspects were not the result of any inventive activity. For example, the claimed invention has one element that does not occur in a first prior art document, but it is common general knowledge that that one element could be added. Generally, it is required to show some kind of hint towards adding that element, or modifying an existing element, before that adding or modifying is considered obvious.

The main problem with obviousness is that you very easily reason with the benefit of hindsight. This is not permitted. You must base your arguments entirely on the prior art, without knowledge of the invention. With hindsight, it is almost always possible to present a series of modifications to a prior art system that result in the claimed invention.

For more information, see When is an invention obvious?.

US patent law requires an invention to be non-obvious. European patent law requires an invention to involve an inventive step. While this may seem at first to be essentially the same, there are important differences.

In Europe, the examiner determines what the differences between the invention and the prior art are. If there are none, the invention is not novel. If there are, the examiner determines what technical problem is solved by adding these elements to the prior art system. He then determines if solving the technical problem by adding those elements would be obvious. If no technical problem can be found, the invention does not involve an inventive step.

In the USA, the examiner directly moves to determining whether it would be obvious to add the novel elements, without trying to establish a technical problem.