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904 How to Search [R-07.2022]

The examiner, after having obtained a thorough understanding of the invention disclosed and claimed in the nonprovisional application, then searches the prior art as disclosed in patents and other published documents, i.e., nonpatent literature (NPL). Any document used in the rejection of a claim is called a reference. An inventor name search should be made to identify other applications and/or patents which may be applicable as references for double patenting rejections. See MPEP § 804.

In all continuing applications, the parent applications must be reviewed by the examiner for pertinent prior art. The examiner must consider prior art which was cited and considered in the parent application. See MPEP §§ 609.02 and 2001.06(b). Where the cited prior art of a parent application has been reviewed, this fact should be made of record in accordance with the procedure set forth at paragraph (J) of MPEP § 719.05, subsection II.A. The examiner must also review the file wrapper history and prior art contained in certain proceedings and specific documents in related PTAB post-grant proceedings. See MPEP § 904.04. For national stage applications filed under 35 U.S.C. 371, the examiner will consider the documents cited in an international search report when the Form PCT/DO/EO/903 indicates that both the international search report and the copies of the documents are present in the national stage application file. See MPEP § 609.03. The first search should cover the invention as described and claimed, including the inventive concepts toward which the claims appear to be directed. It should not be extended merely to add immaterial variants. The examiner’s first Office action on the merits of an application relies on references identified in this initial search.

Following the first Office action, the examiner need not ordinarily make a second search of the prior art, unless necessitated by amendments to the claims by the applicant in a reply to the first Office action, except to check to determine whether any reference which would appear to be substantially more pertinent than the prior art cited in the first Office action has become available subsequent to the initial prior art search.

In the first action on the merits of an application, the examiner must complete the “Search Notes” form to include the classification locations of domestic and foreign patents, abstract collections, and publications in which the search for prior art was made. Other information collections and sources in which the search for prior art was made must also be identified by the examiner. The examiner must also indicate the date(s) on which the search was conducted. Note MPEP § 719.05.

In subsequent actions, where the search is brought up-to-date and/or where a further search is made, the examiner must indicate on the IFW search notes form that the search has been updated and/or identify the additional field(s) of search. See MPEP § 719.05. Any search updates should include all of the relevant or pertinent databases and the search queries and classifications employed in the original search.

904.01 Analysis of Claims [R-08.2012]

The breadth of the claims in the application should always be carefully noted; that is, the examiner should be fully aware of what the claims do not call for, as well as what they do require. During patent examination and reexamination, the claims are given the broadest reasonable interpretation consistent with the specification. See In re Morris, 127 F.3d 1048, 44 USPQ2d 1023 (Fed. Cir. 1997) and In re NTP Inc., 654 F3d 1279, 99 USPQ 1481 (Fed. Cir. 2011). See MPEP § 2111 - § 2116.01 for case law pertinent to claim analysis.

904.01(a) Variant Embodiments Within Scope of Claim [R-07.2022]

Frequently, a claim includes within its breadth or scope one or more variant embodiments that are not disclosed in the application, but which would anticipate or render obvious the claimed invention if found in a reference. The claim must be so analyzed and any such variant encountered during the search should be recognized.

For any claim capable of such treatment (e.g., a machine or other apparatus), the subject matter as defined by the claim may be sketched or diagrammed in order to clearly delineate the limitations of the claim. Two or more sketches, each of which is as divergent from the disclosure as is permitted by the claim, will assist the examiner in determining the claim’s actual breadth or scope. However, an applicant will not be required to submit such sketches of claim structure. In re Application filed November 16, 1945, 89 USPQ 280, 1951 C.D. 1, 646 O.G. 5 (Comm’r Pat. 1951).

904.01(b) Equivalents [R-08.2012]

All subject matter that is the equivalent of the subject matter as defined in the claim, even though different from the definition in the claim, must be considered unless expressly excluded by the claimed subject matter. See MPEP § 2181 - § 2184 for a discussion of equivalents when a claim employs means or step plus function terminology.

904.01(c) Analogous Arts [R-08.2012]

Not only must the art be searched within which the invention claimed is classifiable, but also all analogous arts must be searched regardless of where the claimed invention is classified.

The determination of what arts are analogous to a particular claimed invention is at times difficult. It depends upon the necessary essential function or utility of the subject matter covered by the claims, and not upon what it is called by the applicant.

For example, for search purposes, a tea mixer and a concrete mixer may both be regarded as relating to the mixing art, this being the necessary function of each. Similarly a brick-cutting machine and a biscuit cutting machine may be considered as having the same necessary function. See MPEP § 2141.01(a) for a discussion of analogous and nonanalogous art in the context of establishing a prima facie case of obviousness under 35 U.S.C. 103. See MPEP § 2131.05 for a discussion of analogous and nonanalogous art in the context of 35 U.S.C. 102.

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.

904.02(a) Classified Search [R-07.2022]

A search areas included in a proper field of search normally include the classification locations in which the claimed subject matter of an application would be properly classified at the time of the application's classification or grant of a patent. However, if the above proper classification does not correspond to the subject matter found in the claims (e.g., a situation where the proper classification corresponds to a disclosed, but unclaimed, embodiment), it is not necessary to search areas in which it could reasonably have been determined that there was a low probability of finding the best reference(s).

In outlining a field of search, the examiner should note every classification location (i.e. group/subgroup of the Cooperative Patent Classification and/or class/subclass of the U.S. Patent Classification) under the utilized classification system and other organized systems of literature that may have material pertinent to the subject matter as claimed, including those which have been assigned by a foreign Office, another USPTO examiner, or by the classification contractor. Every group/subgroup and secondary classification area of the Cooperative Patent Classification, class/subclass of the U.S. Patent Classification, digest, and cross-reference art collection pertinent to each type of invention claimed should be included, from the largest combination through the various subcombinations to the most elementary part. The field of search should extend to all probable areas relevant to the claimed subject matter and should cover the disclosed features which might reasonably be expected to be claimed. The examiner should consult with other examiners and/or supervisory patent examiners, especially with regard to applications covering subject matter unfamiliar to the examiner.

The areas to be searched should be prioritized so that the most likely areas of finding relevant prior art are searched first. Though areas to be searched should be prioritized, a thorough and complete search requires the consideration of references from each of the areas where the examiner is likely to find pertinent prior art. For documenting the field of search see MPEP § 719.05. See MPEP § 1302.10 for search information printed on the face of a patent.

904.02(b) Search Tool Selection [R-07.2015]

Detailed guidance on the choice and use of specific search tools can be established only within the context of the special requirements of each Technology Center (TC). However, a general methodology following a “decision tree” process, set forth below, for making broad decisions in search tool selection is suggested.

search Tool Selection Chart

904.02(c) Internet Searching [R-07.2022]

The Internet is an Office-approved search tool that may be considered when planning and conducting a search for an application. The Internet provides the Office the opportunity to enhance operations by enabling patent examiners to efficiently locate and retrieve additional sources of information relating to a patent application.

The Office published a Patent Internet Usage Policy to establish a policy for use of the Internet by the patent examining corps and other organizations within the USPTO. See Internet Usage Policy, 64 F.R. 33056 (June 21, 1999). Articles 9 and 10 of the Patent Internet Usage Policy, which are pertinent to Internet searching and documenting search strategies, are reproduced below. Article 9 primarily addresses using the Internet for unpublished application searches. As mentioned therein, it is necessary that Internet searches related to unpublished applications MUST be limited to the general state of the art and formulated in such a way that protects the confidential proprietary intellectual property.

USPTO personnel may also use the Internet to search, browse, or retrieve information relating to the claimed invention(s) of a published application or proceeding including an application published pursuant to 35 U.S.C. 122(b), a reissue application, or a reexamination proceeding. These applications need not be kept in confidence; therefore, the restriction on the search queries used when performing an Internet search referenced in Article 9 below would not apply to these applications and proceedings. Any search query may include terminology related to the general state of the relevant technology, disclosed features from applicant’s disclosure and claim terminology. See MPEP § 707.05(e) for information pertaining to the citation of electronic documents, MPEP § 719.05, subsection II for documenting an Internet search, and MPEP § 502.03 for information pertaining to communications via electronic mail.

The Internet is generally a public forum and most communications made over the Internet are neither confidential nor secure. All use of the Internet by examiners must be conducted in a manner that ensures compliance with confidentiality requirements in the statutes, including 35 U.S.C. § 122, and regulations. As part of an Internet search, examiners may visit social media websites that provide for public interactions, but are not authorized to participate on these websites or otherwise solicit assistance with patent examination even for published applications. For example, an examiner is not authorized to request users of a website to provide additional information not found on the website, elaborate further on information already posted on the website, or post new information on the website. Additionally, any Internet searching that is conducted is to be limited to searching for the information necessary for examination of the application or proceeding, such as the state of the art or the presence or absence of technical features in the prior art.


The responsibility for formulating individual search strategies lies with individual Patent Examiners, Scientific and Technical Information Center (STIC) staff, and anyone charged with protecting proprietary application data. When the Internet is used to search, browse, or retrieve information relating to a patent application which has not been published, other than a reissue application or reexamination proceeding, Patent Organization users MUST restrict search queries to the general state of the art unless the Office has established a secure link over the Internet with a specific vendor to maintain the confidentiality of the unpublished patent application. Non-secure Internet search, browse, or retrieval activities that could disclose proprietary information directed to a specific application which has not been published, other than a reissue application or reexamination proceeding, are NOT permitted.

This policy also applies to use of the Internet as a communications medium for connecting to commercial database providers.


All Patent Organization users of the Internet for patent application searches must document their search strategies in accordance with established practices and procedures as set forth in MPEP § 719.05 II.

904.03 Conducting the Search [R-07.2022]

It is a prerequisite to a speedy and just determination of the issues involved in the examination of an application that a thorough and complete search, commensurate with the limitations appearing in the most detailed claims in the case, be made in preparing the first action on the merits so that the second action on the merits can be made final or the application allowed with no further searching other than to update the original search. It is normally not enough that references be selected to meet only the terms of the claims alone, especially if only broad claims are presented; but the search should, insofar as possible, also cover all subject matter which the examiner reasonably anticipates might be incorporated into applicant’s amendment. Applicants can facilitate a thorough and complete search by including, at the time of filing, claims varying from the broadest to which they believe they are entitled to the most detailed that they would be willing to accept.

In doing a thorough and complete search, the examiner should find and cite references that, while not needed for rejecting the claims, would be useful for forestalling the presentation of claims to other disclosed subject matter regarded by applicant as their invention, by showing that this other subject matter is old or obvious.

In selecting the references to be used in rejecting the claims, the examiner should carefully compare the references with one another and with the applicant’s disclosure to avoid an unnecessary number of rejections over similar references. The examiner is not called upon to cite all references that may be available, but only the “best.” (See 37 CFR 1.104(c).) Multiplying references, any one of which is as good as, but no better than, the others, adds to the burden and cost of prosecution and should therefore be avoided. The examiner must fully consider all the prior art references cited in the application, including those cited by the applicant in a properly submitted Information Disclosure Statement.

The best reference should always be the one used in rejecting the claims. Sometimes the best reference will have a publication date less than a year prior to the application filing date, hence it will be open to being overcome under 37 CFR 1.130 or 1.131. In such circumstances, if a second reference exists which cannot be so overcome and which, though inferior, is an adequate basis for rejection, the claims should be additionally rejected thereon.

In all references considered, including NPL, foreign patents, and domestic patents, the examiner should study the specification or description sufficiently to determine the full value of the reference disclosure relative to the claimed or claimable subject matter.

904.04 Search of Related Post-Grant Proceedings [R-07.2022]

As explained in MPEP § 904 the examiner is required to review specific papers of PTAB post-grant proceedings in related applications. An application under examination is sufficiently related to another proceeding, such that a complete search requires review of a post grant proceeding, if any one of the following conditions are met:

  • 1) the examined application is the reissue of a patent that was previously or currently is the subject of a post-grant proceeding;
  • 2) the examined application includes a benefit claim under 37 CFR 1.78 to the filing date of a prior US nonprovisional application where the prior US application has issued as a patent and that patent was previously or currently is the subject of a post-grant proceeding;
  • The examiner will be notified when there is a related PTAB post-grant proceeding through the Office’s integrated examination tools. When a PTAB post-grant proceeding has been identified, the examiner must compare the claims of the examined application with that of challenged patents claims to determine whether they have similar scope or similar claim elements . The presence of a recorded terminal disclaimer or a non-statutory double patenting rejection between the application being examined and patent subject to a post-grant proceeding is evidence that the claims have a similar scope or similar claim elements. If the claims do not have a similar scope or similar claim elements the examiner will annotate the search notes indicating the review was completed. See MPEP § 719.05 II.A., element K. When the claims are determined to have a similar scope or similar claim elements, the examiner is required to consider the following:

  • 1. Petition;
  • 2. Patent Owner’s Preliminary Response to the Petition;
  • 3. PTAB’s Decision on the Institution:
    • a. If instituted, further consider the Patent Owner’s response to the Petition;
    • b. If instituted, further consider the Final Written Decision by PTAB;
  • 4. If present, any court decisions (e.g. Federal Circuit) concerning the case and further PTAB proceedings (e.g. PTAB rehearing or remand); and
  • 5. If present, Parties’ supporting evidence, including expert declaration.

Once the examiner has reviewed the required documents, the examiner should document the search as shown in MPEP § 719.05 II.A., element L.

Where the examined application shares a common inventor or common assignee applicant with another application or patent, the examiner should exercise professional judgment in determining whether a complete search would include review of the other application or patent as well as any post-grant proceedings on the other application or patent.

For reexamination proceedings, see MPEP §§ 2256 and 2286.01.



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Last Modified: 02/16/2023 12:58:30