The Importance of Patent Searches

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Two of the main requirements for obtaining a patent on an invention is that it be novel and nonobvious. To be novel, at least some aspect of your invention must be new--that is, it must differ from all previous inventions or existing knowledge. An invention is nonobvious only if someone skilled in the particular field of the invention would view it as an unexpected or surprising development.

To determine whether your invention is novel and nonobvious, you, or someone you hire, must conduct a patent search (also called a “prior art search”).  Doing a patent search involves examining what lawyers call “prior art” to determine if anyone has built, patented or documented the same invention before you. Prior art can come from just about anywhere -- it includes all previous developments that are available to the public. All of the following are prior art:

  • patents for inventions similar to yours publications discussing inventions like yours
  • patents for inventions similar to yours
  • any commercial sale or use of an invention like yours, and
  • any public knowledge or use of a similar invention.

On-Line Patent Searches

Thanks to the Internet, you can now do your own patent search in your spare time, with minimal effort and cost.

U.S. Patent & Trademark Office

You can search the texts or claims of patents for free at the U.S. Patent & Trademark Office (USPTO) at With the USPTO's system you can:

  • search U.S. patents back to 1976
  • search U.S. patent applications back to March 2001 (when they were first published), and
  • make bibliographic searches -- for example, to find out the name, title of invention, or patent number -- of patents from 1790 to the present.

You can easily and quickly download, view, and print the images of any patent before 1976 at the USPTO's website. For example, with broadband Internet service, you can view and print the images of a ten-page patent in less than two minutes! Everything is free on the USPTO's website, except for orders of patents to be sent by mail.

Google Patents

Another free patent website is Google Patents (, an excellent resource that includes text-searchable U.S patents that date back to the 1790s (the beginning of the U.S. patent system). This is more than the USPTO offers since many older USPTO patents are not text-searchable. Many patent searchers find the Google site to be more thorough and easier to use than the USPTO's site.

Fee-based Patent Searching Companies

There are several fee-based patent searching companies:

  • Delphion. You can search U.S. patents and perform patent number searching of worldwide collections for a fee with Delphion at
  • Thomson-Reuters Patent Web. Another fee-based company, Thomson-Reuters Patentweb (, uses optical character recognition (OCR) to incorporate the data from all patents into its data bank.
  • PatentMax. PatentMax ( permits batch downloading.
  • PatBase. PatBase ( is a database that can search many nations' patents back to the 1800s and permits batch downloading.

Offline Patent Searches

Perhaps searching online isn't convenient for you. Or perhaps your idea involves something that is timeless, which means you need to search for old patents -- before 1976.

A great resource for complete patent searching -- from the first patent ever issued to the latest -- is a network of special libraries called Patent and Trademark Depository Libraries (PTDLs). These libraries are well-stocked -- not only with patent materials, but also with reference librarians who will guide you through the patent search process. Every state has at least one; the USPTO maintains an up-to-date list of contact information for all PTDLs at