A patent examiner (or, historically, a patent clerk) is an employee, usually a civil servant with a scientific or engineering background, working at a patent office. Major employers of patent examiners are the European Patent Office (EPO), the United States Patent and Trademark Office (USPTO), the Japan Patent Office (JPO), and other patent offices around the world.
Patent examiners review patent applications to determine whether the invention(s) claimed in each of them should be granted a patent or whether the application should instead be refused. One of the most important tasks of a patent examiner is to review the disclosure in the application and to compare it to the prior art. This involves reading and understanding a patent application, searching the prior art (including prior patent applications and patents, scientific literature databases, etc.) to determine what contribution the invention makes over the prior art, and issuing office actions to explain to the applicants and their representatives (i.e., patent attorneys or agents) any objections that may exist against the grant of a patent. In other words, an examiner reviews a patent application substantively to determine whether it complies with the legal requirements for granting of a patent. A claimed invention must meet patentability requirements of novelty, inventive step or non-obviousness, industrial application (or utility) and sufficiency of disclosure.
Examiners are expected to be efficient in their work and to determine patentability within a limited amount of time. Some patent applications are easy for an examiner to assess, but others require considerably more time. This has given rise to controversy: On April 13, 2007, a "Coalition of Patent Examiner Representatives" expressed concern that in many patent offices, the pressures on examiners to produce and methods of allocating work have reduced the capacity of examiners to provide the quality of examination the peoples of the world deserve [and that] the combined pressures of higher productivity demands, increasingly complex patent applications and an ever-expanding body of relevant patent and non-patent literature have reached such a level that, unless serious measures are taken, meaningful protection of intellectual property throughout the world may, itself, become history.