Invalidity search is performed in relation to an existing patent to prove that claims of the patent are invalid by discovering prior art which is filed before effective filing date of the patent-in-question. In other words, one can say that claims of the patent were granted by mistake by discovering valid prior art which was missed by patent examiner earlier, during examination process of the patent. In invalidity search, claims of the patent are scrutinized to determine the validity of the patent.

An invalidity search is also referred to as validity search. Irrespective of what we name the search, the goal is to check if a patent is valid or invalid.