A validity search, also called opposition or patent invalidity search, examines the validity and strength of a patent. The purpose is to be able is to contest the validity of the patent as a whole or certain claims in the patent, in particular novelty and inventiveness. Such a search is often conducted in response to an accusation of infringement or when the validity of a patent is in question. A validity search looks at, among other things, documents and arguments that were relevant to granting the patent. This in itself can already provide an impression of a patent’s strength.
Furthermore, it also looks at scientific and patent literature that was not considered during the granting procedure. This information, too, may be relevant when it comes to challenging the novelty or inventiveness. Such a search is often conducted in response to an accusation of infringement or when potentially relevant patents have been identified in an infringement search.