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The Inventor's Mentor

June 2008

Searching for Prior Art

This is the sixth column of a series discussing patent law from the point of view of the individual inventor. This series of newsletters will provide you with a valuable guide for your reference. This month I will discuss searching tools available on the Internet.

Before investing large amounts of time and money developing your invention, patenting it and building a prototype, it is wise to conduct a thorough search to make sure that it has not been invented before. It would be unfortunate if after years of work and thousands of dollars in expenses you find out that you cannot get any royalties because the invention was already known and is in the public domain. Even worse, the original inventor may sue you for selling a product that he or she has patented.

A good search is important to avoid wasted investment in time and money later on; however, no search can be guaranteed to be perfect: any publication, anywhere in the world since the invention of the alphabet, could invalidate a patent. In addition, patent databases are enormous and discovering all relevant prior inventions may not be possible within the time and monetary constraints of the search. 

Examiners at the US Patent Office and patent searchers may overlook some relevant inventions: should you apply to patent an idea that is already in the public domain, your patent may erroneously be granted to you, giving you a false confidence to invest heavily in your invention. Later, you may have to sue in court an infringer. You can be assured that during litigation, your opponent will perform as thorough a search as he can, leaving no stone unturned. Your patent may then be found invalid by the court. How much time and money should you initially invest in a search? It should be in proportion to your anticipated investment.

Most industrialized countries provide powerful patent search engine on the Web. However, because the US is the largest market for intellectual property, most patents are first filed in the US. Consequently, the US patent database is the largest and any search should begin with the US databases.

The US search engine is significantly more powerful than those of other countries and it has access to two databases. The first includes issued US patents. The second covers published applications in the examination pipeline, on their way either to become patents or to be rejected. The following search engines can be found on the Web:


US Patent Office: (includes the patent database and the published application database)

European Patent Office:

Japanese Patent Office:

World Intellectual Property Office (WIPO):

Canadian Patent Office:


An international list of patent offices can be found at:


Commercial search engines can also be used to perform your search. Google offers a diversity of tools that can provide you with a point of view different from any government sponsored search engine. A general “Google” search will yield patent as well as non-patent information and may include marketing and manufacturing data. Google also provides a patent search engine at:

Google patent search:

Performing a good search will save you time and money in the long run. My recommendation: Perform your own search on Google and on the US Patent databases. If you determine that your invention already exists, you can stop further effort and expense developing it. If your search doesn’t yield anything, ask a professional to do the search again. If the professional does not find invalidating prior art consider filing for a patent.


Next month we’ll discuss another topic. Stay tuned.


For archived newsletters and a lot of information for the small inventor go to: If you have any question you can contact me at (858)259-2226 or email me at This newsletter should not be construed as legal advice. ©2010 by George Levy.