Burdlaw.com  - Patent Searching Guide

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Type of Patent Search

Objective of the Search

Note: This list is provided for clarity and better communication between clients and attorneys as these terms are often misused and misapplied. This will help you order what you really want.

Clearance Search

This generally means a “right-to-use” search, but may also refer to a “Competition Search”, an “Infringement Analysis”, “Invalidation Opinion” or any other search intended to clear the way for manufacture, use or sale of an item.

Bibliographic Search

Find patents by an inventor or entity

Citation Search

To find where and how often a patent is cited, especially in later patents. This is used to show how important a patent is considered by subsequent inventors.

Company patent search

Find patents published to a specific competitor. A “competition search” or “clearance search” is more extensive and more expensive.

Competition search

Find patents or patent applications published to one or more of a specific list of competitors. This is more extensive than a “Company Search” but less extensive than a “Right to Use Search”.

Continuing Search

Update prior search.

Family search

To locate foreign equivalents of patent. This is used to see if a patented invention can be made, used or sold in some other country

Foreign counterpart search

Same as “Family search”.

Freedom to Use Search

See “clearance search”

Infringement Analysis

An infringement search relative to the claims of just one patent. This generally would result from being accused of infringement by the owner of that patent.

Infringement Search

See “clearance search”

Invalidation Search, Invalidation Study, Invalidation Opinion

Find patent errors or more prior art to kill a patent so that the claimed invention can be made without liability for infringement. Since an opinion is almost always needed, and an opinion would not be written without a search or study, this is most often just called an Invalidation Opinion.

Knock-Out Search

A “knock-out” search is a simplified patentability search that just looks for identical patents but which does not look for ones that might be similar enough to prevent getting a patent.

Legal status search

Find current owner, if fees paid and if reissued or challenged

Patentability Search

Find any similar prior invention of anything which might indicate obviousness. See also, “knock-out” search.

Right to Use Search

Find any patent claims covering a product or service desired to be used, to determine if it would infringe an existing patent. See also “infringement analysis” and “clearance search”.

Rights Termination Search

Same as “Invalidation Search”

State of the art Search

Find the latest patents in a technological area

Validation Search

Find more prior arts that makes an invention less obvious. These are used to enhance the validity of a patent claim, normally in preparation for defending the patent in court against a claim of invalidity.

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Search site hyperlink

Website Name



Official Patent Attorney Roster

If you want this search done right, it is best to contact either BLF or another patent attorney, as a patent attorney is generally an expert at instructing the searcher as to what type of search is needed and providing the information the searcher will need to do a good search most efficiently.


Google Advanced Patent Search or “GAP” search

Advanced form of Google patent search. Called “advanced” because it has advanced features, not because it is for experts only. On the contrary, it is great for novice searchers. Ranks results by relevance. Has quick and easy access to drawings and other parts. Very fast. FREE


Free Patents Online or “FPO” Search

Great site for experienced searches. Register first as registration is free and allows you to get the free patents online. Fast and easy to use. Gives html and pdf images. Ranks patents by relevance. Has simple search or advanced search. Also allows searching of published applications, japanese abstracts, european patents and international (wipo) patents. FREE


United States Patent and Trademark Office Full Text Online Search or “PTO-FT” search

Cumbersome, but most comprehensive for us only searching. Uses tiff images. FREE


Delphion patent searching

Originally set up by IBM but now independently run. $278/month for unlimited searching. For expert searchers. Most comprehensive and sophisticated. Good at patent family searching. Not for novices


Pantros PROSEARCH™ LSA Patent Research

Sophisticated for professional searchers and corporations. Expensive. Top-notch search results. Not for novices.


WIPO Patent Database



Esp@ceNet (EPO)



Additional Links

A very comprehensive listing of additional links.

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Bruce E. Burdick, webmaster