priorart

Prior art is any information that exists before a defined date and could be used to challenge the novelty or non-obviousness of a claimed invention. In patent law, the critical date is usually the filing date of the patent application or an applicable priority date. Prior art can come from a wide range of sources, including earlier patents and patent applications, scientific papers, conference proceedings, theses, product manuals, public demonstrations, and even commercial sales or online publications. For prior art to be relevant, it generally must be publicly accessible and capable of enabling a person skilled in the art to reproduce the invention.

The concept is used to assess patentability in two main ways: novelty and inventive step (often called non-obviousness). If a single prior art reference discloses all essential elements of a claim, the claim may lack novelty and be unpatentable (anticipation). If no single reference shows all elements, a combination of references might render the claim obvious, also undermining patentability. Prior art can also affect the enforceability and validity of an issued patent, and may be used in hearings, reexaminations, or post-grant reviews.

Prior art searches are conducted by applicants during examination, by patent offices, or by third parties, and are an essential part of patent strategy and litigation. Jurisdictional differences exist: some countries restrict or exclude certain disclosures as prior art, and some offer grace periods that allow inventors to disclose before filing without losing patent rights, while others do not.