Money is usually the first reason to do one: a thorough check can prevent filing fees, attorney fees, product launch costs, and later patent infringement disputes over an invention that is not actually new. In a lawsuit, it can also decide whether a patent stands or falls. A prior art search is a review of earlier public disclosures - issued patents, published patent applications, journal articles, product manuals, public uses, sales, and other materials - to find evidence that an invention was already known before a claimed invention date.

Technically, the search is aimed at locating prior art relevant to novelty and nonobviousness under 35 U.S.C. § 102 and § 103, as revised by the Leahy-Smith America Invents Act of 2011. In the United States, patent examiners at the USPTO perform their own examination search, but an applicant, competitor, or litigation team often conducts a separate search before filing, before licensing, or before challenging a patent's validity. Search results may also trigger a duty to disclose material references to the USPTO under 37 C.F.R. § 1.56.

In practice, the quality of the search can change case value. Strong prior art can support invalidity defenses, reduce settlement leverage, or block a weak application before more money is spent. A weak or incomplete search can leave a business exposed to avoidable filing costs and expensive federal litigation.