A person having ordinary skill in the art (abbreviated PHOSITA), a person of ( ordinary) skill in the art ( POSITA or PSITA), a person skilled in the art, a skilled addressee or simply a skilled person is a legal fiction found in many patent laws throughout the world. This hypothetical person is considered to have in a particular technical field (an "art"), without being a genius. This measure mainly serves as a reference for determining, or at least evaluating, whether an invention is non-obvious or not (in U.S. patent law), or involves an inventive step or not (in European patent laws). If it would have been obvious for this fictional person to come up with the invention while starting from the prior art, then the particular invention is considered not patentability.
In some patent laws, the person skilled in the art is also used as a reference in the context of other criteria, for instance in order to determine whether an invention is sufficiently disclosed in the description of the patent or patent application (sufficiency of disclosure is a fundamental requirement in most patent laws), or in order to determine whether two technical means are equivalents when evaluating infringement (see also doctrine of equivalents).
In practice, this legal fiction is a set of legal fictions which evolved over time and which may be differently construed for different purposes. This legal fiction basically translates the need for each invention to be considered in the context of the technical field it belongs to.
The person skilled in the art is described in Beloit Canada Ltd. v. Valmet Oy:
the technician skilled in the art but having no scintilla of inventiveness or imagination; a paragon of deduction and dexterity, wholly devoid of intuition; a triumph of the left hemisphere over the right. The question to be asked is whether this mythical creature (the man in the Clapham omnibus of patent law) would, in the light of the state of the art and of common general knowledge as at the claimed date of invention, have come directly and without difficulty to the solution taught by the patent. Beloit Canada Ltd. v. Valmet Oy (1986), 8 C.P.R. (3d) 289 at p. 294.
The EPC also refers to the skilled person in , which requires that "the European patent application must disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art".
Still further, the Protocol on the Interpretation of refers to the skilled person. Article 1, 2nd sentence, states that "nor should it Article be taken to mean that the claims serve only as a guideline and that the actual protection conferred may extend to what, from a consideration of the description and the drawings by a "person skilled in the art", the patent proprietor has contemplated". Protocol on the Interpretation of Article 69 EPC of 5 October 1973 as revised by the Act revising the EPC of 29 November 2000
The European Patent Office provides guidelines "Person skilled in the art" that set forth some of the skilled person's capabilities.
A related concept is the "business person", who is also a notional person. It is used at the EPO when assessing inventive step of an invention involving both technical and non-technical elements. The business person "represents an abstraction or shorthand for a separation of business considerations from technical". T 1463/11 (Universal merchant platform / CardinalCommerce) of 29.11.2016, Reasons 15.
The PHOSITA appears again in slightly different words in the provision requiring a proper disclosure:
It is well known that it may take a few months or a couple of years for a paper to be published in a academic journal. The date of a sanctioned prior art can be a little later than the patent's application date:
Importantly, Justice Anthony Kennedy's opinion stated, "A person of ordinary skill is also a person of ordinary creativity, not an automaton." Although the Court's opinion acknowledged other Federal Circuit cases that described a PHOSITA as having "common sense" and who could find motivation "implicitly in the prior art," Kennedy emphasized that his opinion was directed at correcting the "errors of law made by the Court of Appeals in this case" and does not necessarily overturn all other Federal Circuit precedent.
Once the PHOSITA is properly defined, KSR v. Teleflex described how obviousness should be determined:
For example, the Germany Patent Act ( Patentgesetz) requires that the invention "cannot be derived by a Fachmann from the state of the art in an obvious manner"."... wenn sie sich für den Fachmann nicht in naheliegender Weise aus dem Stand der Technik ergibt.", Art. 4 of the Patentgesetz. The word Fachmann (an ordinary German word meaning somebody who has professional knowledge in a field) is made specific by ständiger Rechtsprechung (usual court opinion) as a "specialist with average knowledge and talent whom one would ordinarily ask to seek a solution for the (objective) problem the invention deals with""Sachverständiger mit durchschnittlichem Wissen und Können, den man üblicherweise mit der Lösung der (objektiven) Aufgabe der Erfindung betrauen würde" (stRspr - BPatG Mitt. 84, 213, T 32/81 Abl. 1982, 225)