904.02 General Search Guidelines [R-07.2022]

In the examination of an application for patent, an examiner must conduct a thorough and complete search of the prior art. A search is considered thorough when all areas with the highest probability of finding prior art relevant to the invention as it is claimed and described in the specification are identified for search. Planning a thorough search of the prior art requires three distinct steps by the examiner: (A) identifying the field of search; (B) selecting the proper tool(s) to perform the search; and (C) determining the appropriate search strategy for each search tool selected. A search is considered complete when each of the identified areas are fully considered.

When determining the field of search, three reference sources must be considered – domestic patents (including patent application publications), foreign patent documents, and nonpatent literature (NPL). A thorough and complete search will include the identification and review of the areas within these sources with the highest probability of including prior art, thus none of these sources can be eliminated from the search unless the examiner has and can justify a reasonable certainty that no references, more pertinent than those already identified, are likely to be found in the source(s) eliminated. The search areas should cover the claimed subject matter and should also cover the disclosed features related to the inventive concept of the claims which might reasonably be expected to be claimed. The field of search should be prioritized, starting with the area(s) where the invention would most likely be found in the prior art.

Having determined the field of search, the examiner should then determine what search tools should be employed in conducting the search. Examiners are provided access to a wide variety of both manual and automated search tools. Choice of search tools is a key factor in ensuring that the most relevant prior art is found during the search. The choice of search tools to be used is based on the examiner’s knowledge of the coverage, strengths and weaknesses of the available search tools that are appropriate for use in an examiner’s assigned art. For example, a search tool may cover foreign patent documents; but, if that coverage does not meet the examiner’s current search needs, this should be taken into consideration by the examiner who may choose to employ other search tools in order to remedy the deficiency.

Search tool knowledge is particularly important for examiners in arts (e.g., very active, high technology) where patent documents may seriously lag behind invention and, consequently, represent a reference source of limited value. These examiners must take special care to ensure that their searches include consideration of NPL and employ the effective use of tools specialized to cover NPL pertinent to their search needs.

Search needs in some technologies (e.g., chemical structures, DNA sequences) are very specialized and can only be met through additional use of specific search tools specially constructed and maintained to respond to those needs. These tools cover all three reference sources – domestic patents (including patent application publications), foreign patent documents, and NPL.

In recognition that there are many available NPL search tools and their use is often complex, examiners have been provided and are encouraged to use the services of trained professional online search personnel located in the Technology Centers’ EICs for NPL searching. See MPEP § 901.06(a) for services available in STIC.

In crowded, highly developed arts where most claimed inventions are directed to improvements, patent documents, including patent application publications, may serve as the primary reference source. Search tool selection in such arts may focus heavily on those providing patent document coverage.

Automated search tools covering patent documents usually provide both a classified and text search capability. Text search can be powerful, especially where the art includes well-established terminology and the search need can be expressed with reasonable accuracy in textual terms. However, it is rare that a text search alone will constitute a thorough search of patent documents. Some combination of text search with other search criteria (e.g., classification, chemical structure, or molecular sequence) would be a normal expectation in most technologies.

Examiners will recognize that it is sometimes difficult to express search needs accurately in textual terms. This occurs often, though not exclusively, in mechanical arts where, for example, spatial relationships or shapes of mechanical components constitute important aspects of the claimed invention. In such situations, text searching can still be useful by employing broader text terms, with or without classification parameters. The traditional method of browsing all patent documents in one or more classifications will continue to be an important part of the search strategy when it is difficult to express search needs in textual terms.

Having determined what search tool(s) should be used to conduct the search, the examiner should then determine the appropriate search strategy for each search tool selected. The appropriate search strategy should be determined by the examiner on a case-by-case basis along with consultation with other examiners, supervisory patent examiners, and/or trained professional online search personnel, where appropriate.

In order for examiners to acquire specialized skills needed to determine an appropriate field of search in their specific arts, each Technology Center may develop specific supplemental guidance and training for its examiners. This training will augment general training and information on search tools that is normally provided through the Office of Patent Training and Search and Information Resources Administration.