Searching for a US Patent

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What is a Patent and Trademark Depository Library?

Searching for a US Patent

One idea that has remained consistent since the inception of patent law is that patent information should be available to the public and easy to obtain. This does not mean, however, that conducting such a free patent search will be easy. The sheer number of issued patents makes finding what is called prior art a painstaking task. Two places where you can obtain patent information are the Scientific and Technical Information Center of the US Patent and Trademark Office and the Patent Search Room. Both are located in Alexandria, Va.

However, if you want to conduct a patent search closer to home, you can locate the library nearest you that has been designated as a Patent and Trademark Depository Library. At such a place, you can inspect and obtain copies of patents you find there. The scope of these Depository Libraries varies from only recently issued patents to all those granted back to 1790. At a Depository Library, you'll be able to obtain help from an employee who understands both the US Patent Classification System as well as patent documents and forms necessary for filing. Some copies of lists of original patents or of cross-referenced patents can also be ordered from the US Patent and Trademark Office. For more information on how to conduct a patent search, visit



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