A Patent Validity Search or Patent Invalidity Search involves exhaustive patent and non-patent search. In this search patent and non-patent literature is located that predate a critical date that corresponds to a subject patent. The critical date is the date of invention. In case of continuation in part and divisional patents, the priority date is taken as the critical date. These dates are governed by 35 U.S.C. § 102(a), (b), or (e). It also involves analysis of image file wrapper to see the reason of allowance of a particular subject patent.
According to the study “Patent Validity Litigation in the Courts”, 2001 (by Janis) of Federal Circuit and District Court cases, 54% of the court decisions patent claims sustained a validity challenge. Thus, 46% of the decisions found patent invalidity.
Patent examiners have limited time and resources to conduct their prior art searches. Thus, there is a high probability to gather court admissible evidences by conducting a detailed validity or invalidity search. These court admissible evidences can be used to question the patent’s claims and to prove that the patent should not have been granted.