A validity (or invalidity) search aims at finding material (patent or non-patent) which can influence the validity of a granted patent. The results of a validity search can e.g. be used in an opposition procedure, i.e. a patent legal procedure to invalidate an existing patent. This can be the case when one is hindered by a competitor’s patent, e.g. in the case of possible infringement.
Validity analyses are also used to determine the quality of a patent portfolio in the case of licensing or takeovers.
The approach used in validity searches is comparable to that of a novelty search. However, the search is generally both broader and deeper. Relevant literature must dated before the filing of the patent in question.
In the case of oppositions, validity searches will almost always be conducted in cooperation with a patent attorney, because the latter has the responsibility for drafting a notice of opposition.