Patent Searching

Once you decide that your invention is patentable, you will need to do a preliminary patent search. The best place to begin this is at your closest Patent and Trademark Depository Library. An average search takes about 13 hours, so allow yourself plenty of time. You don’t have to complete the search all at once.

The 7-Step Strategy shown below is put forth by the United States Patent and Trademark Office. It is a simplified instruction manual for doing a search at a Patent and Trademark Depository Library. The search approach is based on U.S. patent classifications instead of keywords. Patents granted prior to 1976 are not searchable by keywords, only by classification or patent number. Newer patents can be difficult to find given that the language of patents can be strange. For example, a cuckoo clock is called a “horological instrument with musical simulated avian.” If you can figure out what classification and sub-classification numbers your invention falls under, you can search by those numbers with greater success. Below are the 7 steps. To watch a 10 minute tutorial put together by Auburn Universities Libraries, Auburn, AL, please click here.

  1. Describe your invention.
  2. Find relevant classes and subclasses using the Index to US Patent Classification (USPC) System
  3. Verify the relevancy using the Classification Schedules.
  4. Confirm the scope using the Classification Definitions.
  5. Review your results looking at full text documents (PatFT) and published applications (PatAPP).
  6. From the USPCs, find relevant Cooperative Patent Classifications (CPCs) and review these results.
  7. Use Espacenet to conduct a classification search of CPCs.
    • Search and review these in the USPTOs PatFT and PatAPP databases.


If you decide that you want patent protection that reaches farther than the U.S., you will need to search at least the European and Japanese patent systems. Some searching can be done at your local Patent and Trademark Depository Library. Once your preliminary search is done, you may want to retain the services of an attorney who practices intellectual property law. The U.S. Patent and Trademark Office maintains a Roster of Patent Attorneys and Agents Registered to Practice Before the PTO. Your preliminary search should cut costs. WARNING: there are many unscrupulous folks out there who would love to take your money. Don’t trust your invention to just anyone. Find out more here: Beware of Invention Promotion Scams!