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Prior art

Prior art (also known as state of the art, which also has other meanings, or background art[1]), in most systems of patent law,[2] constitutes all information that has been made available to the public in any form before a given date that might be relevant to a patent's claims of originality. If an invention has been described in prior art, a patent on that invention is not valid.

Information kept secret, for instance, as a trade secret, is not usually prior art, provided that employees and others with access to the information are under a non-disclosure obligation. With such an obligation, the information will typically not be regarded as prior art. Therefore, a patent may be granted on an invention, although someone else already knew of the invention. A person who used an invention in secret may in some jurisdictions be able to claim "prior user rights" and thereby gain the right to continue using the invention. As a special exception, earlier-filed and unpublished patent applications do qualify as prior art as of their filing date in certain circumstances.

In order to anticipate a claim, prior art is generally expected to provide a description sufficient to inform an average worker in the field (or the person skilled in the art) of some subject matter falling within the scope of the claim. Prior art must be available in some way to the public, and in many countries, the information needs to be recorded in a fixed form somehow. Prior art generally does not include unpublished work or mere conversations (though according to the European Patent Convention, oral disclosures also form prior art see ). It is disputed whether traditional knowledge (e.g., of medical properties of a certain plant) constitutes prior art.

Patents disclose to society how an invention is practiced, in return for the right (during a limited term) to exclude others from manufacturing, selling, offering for sale or using the patented invention without the patentee's permission. Patent offices deal with prior art searches in the context of the patent granting procedure. To assess the validity of a patent application, patent offices explore the prior art that was disclosed before the invention occurred (in the United States) or before the filing date (in the rest of the world).


Other considerations

Although patents normally go to the first inventor under a first-to-file system, an inventor who keeps the information secret or does not publish it does not establish prior art and loses the right to the patent. Without prior art, a subsequent inventor can get a valid patent on the same invention and then apply it against earlier inventor(s). An earlier inventor can forestall such an act by a subsequent inventor by recognizing the invention and applying for a patent, or by publishing details of how to practice the invention, thus creating prior art.

Usage in litigation

Arguments claiming prior art are used both in defending and attacking patent validity. In one U.S. case on the issue, the court said:

"One attacking the validity of a patent must present clear and convincing evidence establishing facts that lead to the legal conclusion of invalidity. 35 U.S.C. 282. To establish invalidity under 35 U.S.C. 103, certain factual predicates are required before the legal conclusion of obviousness or nonobviousness can be reached. The underlying factual determinations to be made are
(1) the scope and content of the prior art;
(2) the differences between the claimed invention and the prior art;
(3) the level of ordinary skill in the art; and
(4) objective evidence of non-obviousness, such as commercial success, long-felt but unsolved need, failure of others, copying, and unexpected results."
Graham v. John Deere Co., 383 U.S. 1, 17, 148 USPQ 459, 467 (1966).[3][4]

Types of prior art searches


A "novelty search" is a prior art search that is often conducted by patent attorneys, patent agents or professional patent searchers before an inventor files a patent application. A novelty search helps an inventor to determine if the invention is novel before the inventor commits the resources necessary to obtain a patent. The search may include searching in databases of patents, patent applications and other documents such as utility models and in the scientific literature. A search of this type is also conducted by patent examiners during prosecution of the patent application. For instance, examiner's search guidelines applicable to the United States are found in the U.S. Manual of Patent Examining Procedure (MPEP) 904.02 General Search Guidelines, Prior Art, Classification, and Search.[5]


A "validity search" is a prior art search done after a patent issues. The purpose of a validity (or invalidity) search is to find prior art that the patent examiner overlooked so that a patent can be declared invalid. This might be done by an entity infringing, or potentially infringing, the patent, or it might be done by a patent owner or other entity that has a financial stake in a patent to confirm the validity of a patent.


A clearance search is a search of issued patents to see if a given product or process violates someone else's existing patent. If so, then a validity search may be done to try to find prior art that would invalidate the patent. A clearance search is a search targeting patents being in force and may be limited to a particular country and group of countries, or a specific market.

Duty of disclosure

In the United States, inventors and their patent agents or attorneys are required by law to submit any references they are aware of to the United States Patent and Trademark Office that may be material to the patentability of the claims in a patent application they have filed. The patent examiner will then determine if the references qualify as "prior art" and may then take them into account when examining the patent application. If the attorney/agent or inventor fails to properly disclose the potentially relevant references they are aware of, then a patent can be found invalid for inequitable conduct.[6]

Japan also has a duty of disclosure.[7][8][9]

Australia has abolished its duty of disclosure with regard to the results of documentary searches by, or on behalf of, foreign patent offices, except where:

(a) normal exam was requested before April 22, 2007,
(b) the foreign patent office search issued before April 22, 2007, and
(c) acceptance (allowance) was officially advertised before July 22, 2007.[10]

Public participation in patent examination

With the advent of the Internet, a number of initiatives have been undertaken to create a forum where the public at large can participate in prior art searches. These forums have been related to both issued patents and pending patent applications.

Pending patent applications

More recently, different attempts to employ open Internet-based discussions for encouraging public participation commenting on pending U.S. applications have been started. These may take the form of a wiki:

Patent examiners often use the online encyclopedia Wikipedia as a reference to get an overall feel for a given subject.[11][12] Citations of Wikipedia as actual prior art can be problematic, however, due to the fluid and open nature of its editing, and Patents Commissioner Doll said the agency used Wikipedia entries as background and not as a basis for accepting or rejecting an application.[12]

See also

Notable prior art databases

For other patent search services, see Category:Patent search services.


Further reading

External links

Official institutions

  • WIPO (World Intellectual Property Organization)
    • PatentScope, WIPO search tool for international and national patent collections.
    • WIPO Gold, Search national patent offices including US, Japan, the UK, and others. A free public search tool gateway for WIPO's global collections of searchable IP data."
  • USPTO The U.S. Patent and Trademark Office.
  • EPO (European Patent Office)
    • EPO
    • ("The state of the art", search)
    • ("State of the art", examination)

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