Seven Step Strategy for conducting preliminary searches of U.S. patents and published applications

This is a suggested Seven Step Strategy for conducting preliminary searches of U.S. patents and published applications using free online resources of the USPTO and its bi-lateral partner EPO (European Patent Office).  Patent and Trademark Resource Centers (PTRCs) ( are available nationwide to provide training on this Seven Step Strategy.

PTRCs provide online access to the PatFT (Patents Full-Text and Image) and AppFT (Applications Full-Text and Image) databases on the USPTO website and the Espacenet Worldwide Database on the EPO website. In addition, most PTRCs provide access to additional USPTO patent databases available through PubWEST (Public version of the Web-based Examiners Search Tool) and PubEAST (Public version of the Examiners Assisted Search Tool). Always call your nearest PTRC to make an appointment before visiting to make the best use of your time.

The use of patent classification in searching U.S. patents and published applications usually results in a more comprehensive search than one done by word and phrases (keyword searching). Because keyword searching must anticipate the often technical language of patents, it serves best as a supplement to a classification search. Accordingly, patent classification searching is the focus of the Seven Step Strategy.

The USPTO has transitioned from using the over 100 year old U.S. Patent Classification (USPC) system to Cooperative Patent Classification (CPC), a new classification system jointly developed with the European Patent Office (EPO). The USPTO currently only uses CPC for classifying new utility patent documents; however, it will continue to use U.S. Patent Classification for classifying design and plant patents. This version of the Seven Step Strategy reflects this transition to the primary use of Cooperative Patent Classification in utility patent publication searching.

The Seven Steps in a Preliminary Search of U.S. Patents and Published Patent Applications

  1. Brainstorm terms to describe your invention based on its purpose, composition and use.
  2. Use these terms to find initial relevant Cooperative Patent Classification using the USPTO website’s Site Search box( In the Site search box found in the top right hand corner of the home page enter “CPC Scheme [plus keywords(s) describing invention]”; for example, if you were trying to find CPC Classifications for patents related to umbrellas, you would enter “CPC Scheme umbrella”. Scan the resulting classification’s Class Scheme (class schedules) to determine the most relevant classification to your invention. If you get zero results in your Site Search, consider substituting the word(s) you are using to describe your invention with synonyms, such as the alternative terms you came up with in Step 1. For example, if you find searching for “CPC Scheme car mirror” is getting unsatisfactory results, try searching instead with “CPC Scheme vehicle mirror.” (If you continue to be disappointed with the CPC Classification search results, look for your search word in the International Patent Classification Catchword Index¬ion=cw; CPC is based on International Patent Classification).
  1. Verify the relevancy of CPC classification you found by reviewing the CPC Classification Definitionlinked to it (if there is one).
  2. Retrieve U.S. patent documents with the CPC classification you selected in the PatFT (Patents Full-Text and Image) database ( Review and narrow down the most relevant patent publications by initially focusing on the front page information of abstract and representative drawings.
  3. Using this selected set of most relevant patent publications, review each one in-depth for similarity to your own invention, paying close attention to the additional drawings pages, the specification and especially the claims. References cited by the applicant and/or patent examiner may lead you to additional relevant patents.
  4. Retrieve U.S. published patent applications with the CPC classification you selected in Step 3 in the AppFT (Applications Full-Text and Image) database ( Use the same search approach used in Step 4 of first narrowing down your results to the most relevant patent applications by studying the abstract and representative drawings of each on its front page. Then examine the selected published patent applications closely, paying close attention to the additional drawings pages, the specifications and especially the claims.
  5.  Broaden your search to find additional U.S. patent publications using keyword searching in PatFT or AppFT databases, classification searching of non-U.S. patents on the European Patent Office’s Worldwide Espacenet patent database ( and searching non-patent literature disclosures of inventions using the free electronic and print resources of your nearest Patent and Trademark Resource Center (


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