There is more than one type of patent searching
The term “patent searching” frequently leads to confusion because it may refer to any one of several different types of searching. Two of the most common types of patent search are (1) patentability searches (also called novelty searches, prior art searches or invalidity searches depending on their purpose) and (2) a freedom-to-operate search (often called an infringement search). The fundamental difference between these two types of patent search is often not appreciated.
Patentability searches and freedom-to-operate searches
In a nutshell, a patentability search aims to establish whether a patent can be granted (or should have been granted) for a concept by looking for pre-existing disclosures, (often, but not always, patent applications) which show that the concept is known or obvious; conversely, a freedom-to-operate search considers whether a proposed product or process may fall within the scope of any granted patents in the specific country/countries of interest.
It is important to appreciate that a patentability search does not assess freedom to operate. Documents uncovered in a patentability search may sometimes be relevant to freedom to operate, but only to a limited extent. Indeed, it is important to appreciate that even having a granted valid patent does not mean that you have freedom-to-operate. The value of a patent is that it enables you to control the market for products or processes within the scope of the claims; it does not confer freedom from infringing third party patents.
Conversely, freedom-to-operate searches are not patentability searches. They have a different focus and will, for example, exclude patent publications that are sufficiently old (usually at least 20 years old) that any patents resulting from them must have expired, and so not be relevant to freedom-to-operate, whereas documents of any age are relevant to patentability.
By way of an example to further explain the difference between the two types of search, imagine a person who was the first to invent a bicycle having multiple selectable gears. They carry out a patentability search and find that no-one has suggested the idea before. They can readily obtain a valid granted patent and monopolise bicycles with multiple selectable gears for a period of time. However, when they come to sell their product, they may find that they infringe an earlier patent for the whole idea of a bicycle; or for the mechanism used to make the chain; or the material used to make the wheels… a freedom-to-operate search would have considered these topics but a patentability search only considered whether the use of multiple selectable gears was known.
Thus, patentability and freedom-to-operate are very different concepts, and patentability and freedom-to-operate searches are different in nature.
Generally speaking, typical freedom-to-operate searches are quite a lot more expensive than typical patentability searches. Many more documents must be considered by the searcher and the documents which are found require a more detailed analysis.