Prior Art

What It Means

Prior art is the body of existing knowledge that patent examiners use to determine whether an invention is truly novel and non-obvious. It includes previously granted patents, published patent applications, academic papers, conference presentations, products sold on the market, public demonstrations, and even oral disclosures — essentially anything that was publicly available before the patent application's filing date. When a patent examiner reviews an application, they search prior art databases to find references that describe the same or similar inventions. If prior art shows that the invention was already known, the claims will be rejected for lack of novelty. If prior art shows components that could be combined to arrive at the invention, the claims may be rejected as obvious. Prior art searches are also critical in patent litigation: defendants accused of infringement frequently argue that the patent should never have been granted because the examiner missed relevant prior art. This is the basis for invalidation defenses and inter partes review proceedings. Companies investing in R&D conduct their own prior art searches before filing to avoid wasting money on applications likely to be rejected. Patent attorneys use prior art strategically — both to strengthen their own applications by distinguishing from existing work, and to challenge competitors' patents by finding references the original examiner may have missed. The completeness of prior art searching directly affects the quality and defensibility of issued patents.

Frequently Asked Questions