Person having ordinary skill in the art

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 the normal skills and knowledge 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 patentable.

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.