March's advice article

Searching with CPC

One of the first steps toward patenting an invention is to make sure the invention does not already exist.

But with close to 9 million issued U.S. patents alone (not to mention the many more millions of foreign patents and technical documents), how is anyone able to quickly search and locate prior art during the course of an examination? All patent office around the world use some sort of classification system that is capable of organizing and cataloging all of the technologies known to mankind. By learning and using the appropriate patent classification system, patent applicants that locate technology related to their own inventions.

The Cooperative Patent Classification (CPC) effort is a joint partnership between the United States Patent and Trademark Office (USPTO) and the European Patent Office (EPO) to “harmonize” patent classification. The new system takes components from each office’s existing systems—European Classification (ECLA) and United States Patent Classification (USPC), respectively—and migrates toward a common classification scheme for both offices.

On December 31, 2014, after a year-long transition, the USPTO began exclusively using CPC to classify utility patent applications. The old USPC system is now a static document collection that remains searchable. Design and plant applications will continue to be classified in USPC.

Among the many benefits from using this new classification system are:

  • Access to a greater number of documents from patent offices around the world
  • Improved navigation and understanding of a single classification system
  • Improved consistency of classified search results across intellectual property offices
  • Maintained classification schemes through active and adaptive examiner and user involvement.

There are many resources to help new CPC users learn the system, including various CPC computer-based training modules that provide an introduction and detailed discussion of the new classification schemes and definitions:

All USPTO search tools currently available to users on have been updated to include CPC symbols. User search tools currently available are:

  • Patent Full-Text and Image Database (PatFT) - Using PatFT, users have access to a collection of full-text patents issued from 1976 to the present and PDF images for all patents from 1790 to the present.
  • Patent Application and Image Database (AppFT) AppFT provides access to a collection of full-text and image versions of published patent applications.
  • Global Patent Search Network (GPSN) GPSN gives users full-text access to multiple international patent collections. The initial collection available is Chinese patent documentation from the State Intellectual Property Office (SIPO) of the People’s Republic of China. Users can search published applications, granted patents, and utility models from1985 to 2012. The data available includes full-text Chinese patents, English machine translations, and full document images.

To search CPC schemes and definitions, users can access various Office of Patent Classification (OPC) tools, including:

Additional support for users is provided through the Public Search Facility at USPTO headquarters in Alexandria, Virginia, as well as Patent and Trademark Resource Centers (PTRCs) across the country. While PTRCs maintain local search resources and may offer training in patent search techniques, the USPTO Public Search Facility provides the public access to patent and trademark information in a variety of formats including online, microfilm, and print. Whether in the Public Search Facility or PTRC, trained staff is available to assist public users.

Lastly, visit for additional information on bilateral CPC training initiatives, press releases, CPC revision projects, publications, and upcoming CPC-related events.

The CPC Implementation Team contributed to this article

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The USPTO gives you useful information and non-legal advice in the areas of patents and trademarks. The patent and trademark statutes and regulations should be consulted before attempting to apply for a patent or register a trademark. These laws and the application process can be complicated. If you have intellectual property that could be patented or registered as a trademark, the use of an attorney or agent who is qualified to represent you in the USPTO is advised.