Patent invalidity/validity searches are conducted to either validate the claims made by a patent or to invalidate one or more claims of a competitor’s patent. It is the first step taken by a company when faced with a patent infringement lawsuit. Validity searches are also conducted to check the strength of a granted patent while exploring the available licensing options. An Invalidity Search is a prior art search done after a patent issues. The purpose of an invalidity (or validity) search is to find prior art that the patent examiner overlooked so that a patent can be declared invalid. As a searcher, we are expected to dig deep into the domain to find critical prior art overlooked by the patent examiner, which would allow the client to challenge another’s patent (“invalidity”) or be prepared to defend a patent infringement allegation by a competitor (“validity”).