Should I Do A Prior Art Search?
Mark Levy

If you're a serious inventor, one of the many legal terms you'll soon come across is 'prior art.' For inventors, prior art means any recorded knowledge about your idea that may have existed - before you thought it up.

Since our whole patent system is based on ownership of original ideas, it's essential to know what, if any, prior art is out there. There are three really good reasons for searching:

1) Discover if you can obtain a patent on the idea, product or invention.
2) Determine whether you'd be infringing someone else's patent if you started manufacturing a product.
3) See whether others have been close to solving your problem with their own inventions.
My lawyerly advice is always do a reasonable search before you submit your patent application. The last thing you want is to expend money and effort on your Great Invention only to discover your idea was patented long ago. Or, a valid patent still exists, and moving on it means you'd infringe or need a license agreement not to infringe.

Conducting the Search

Now that I've convinced you to do a prior art search with vigor, here's how I recommend you go about it, in roughly this order.

First Step: Common Sense

It's almost too obvious to note, but begin your prior art search in the open marketplace. By this I mean walk through your local mall or hardware store, or visit the obvious places where your invention might be sold or used whether that's aboard a ship or in an operating room.

Equally obvious is general searching via the Internet. Take some time at it - an hour minimum - using your favorite search engine to look for descriptions of your invention or what it solves. Remember: Prior art doesn't refer only to patents listed on the U.S. Patent Office website. Prior art is everything that's ever been recorded on any idea or invention. So the Internet is a great resource.

But don't stop there.

Searching the USPTO Website

Your very next action is searching the patent database on the U.S. Patent and Trademark Office website. The price is right (free). The website for searching - - lets you search all text of all U.S. patents granted since 1976. Patents granted between 1790 and 1976 are accessible on the Internet only by their numbers or classifications. While you can view those older patents if you know their patent numbers or current U.S. classifications, you don't have search capability on their text. An excellent alternative is This site allows you to see the drawings and issued patents as printed. Consider checking the global patent search database at

Here's how searching the USPTO website saved me from going forward with a great idea that wasn't original. One morning I was awakened by skunk odor outside the house. That gave me the idea of inventing an alarm clock that wakens the user by odor - a nice one, I mean. Being a wise inventor, I searched the USPTO website for prior art by typing in words like 'clock,' 'timepiece,' or 'time' and ended those criteria with 'odor,' and 'scent.' Then I added 'alarm' and 'timer' in more combinations. Soon enough I discovered prior art indeed existed - one patent. So I dropped the idea. By learning early on the concept was already disclosed, I saved myself a ton of time and effort not preparing a patent application that would be turned down anyway.

Great as it is, having a database searchable only back to 1976 does have its limits. For inventions involving biotechnology or ray guns, that's probably fine since few cloning techniques or lasers existed before 1976. But should you be inventing a new mousetrap or printing press, it's likely a patent did, or does, exist on those. So you'd have to access patents granted before 1976 - either by visiting the USPTO in Washington, D.C., or hiring someone as I'll explain.

NOTE: When searching the USPTO website, take care to anticipate what a patent attorney, as opposed to normal people, might call something. An attorney might call an ordinary pencil 'a substantially elongated cylindrical writing implement.' But if you search on only the word 'pencil' you may never find an important piece of prior art on the Internet. At the risk of over-simplification, may I suggest a good old thesaurus to come up with word alternatives.

Visit a Depository Library

If by this time you still haven't found prior art, then a next step might take you in person to a Patent and Trademark Depository Library - or PTDL - of which there are 86 in the 50 states and Puerto Rico. A complete listing, by state, is on

Since the Internet provides so much function, the PTDLs' usefulness has somewhat diminished the past few years. And they don't all provide exactly the same patent search resources. However, a call to the USPTO and to PTDLs in Denver, CO; Sunnyvale, CA; and New York City, revealed the existence of tools you can't get on the Internet. One such tool - Cassis - is a CD-ROM database allowing more robust searches than you can do at home. Subscribing to it would cost you $300 annually, and its use is free at PTDLs.

PTDL facilities offer other search resources you simply can't get online, such as computerized guides and publications, and human help. For example, the Sunnyvale PTDL reports they sometimes have a volunteer on hand to help searchers. And the New York City facility offers free patent searching classes. My recommendation is if a PTDL is within driving distance, contact them to see if the patent search tools they provide would be worth your while to pay a visit. You may also wish to investigate a PTO satellite office, such as the ones located in Detroit Michigan, Dallas Texas, and Denver Colorado.

Hire A Patent Searcher

If you're investing a lot to get your invention into production, you definitely want to know what, if any, prior art exists to avoid infringement or license fees later. So the expense of hiring a professional searcher may be very justified. For example, a pro would know about searching for prior art within official patent classes of which there are about 500, and patent sub-classes of which there are some 350,000. That's a lot of places prior art can hide, and a pro can quickly overcome the severe limitations of doing it yourself.

Since the best search is still done at the USPTO in Washington, D.C., hire someone who'll go there. Be prepared to spend anywhere up to $2,000 for a professional search - money well spent if you plan to manufacture and market your invention in a big way.

Some Words of Caution

No prior art search - done on your own or by a pro - can guarantee all existing prior art will be uncovered.

Some time ago while working for a corporation, I received notice a patent was granted on an application my company filed. Just weeks later the USPTO granted another patent on virtually the same invention from another company. By coincidence, two inventors had filed separate applications about the same time. Both applications were reviewed for prior art by the USPTO. But the respective examiners didn't look in the same places, so patents issued on both. It was clearly a USPTO error, since an invention can by protected by only one patent. Fortunately for the inventors, they resolved it by entering into cross-licensing agreements with each other.

Should you search for prior art? You bet. If you do discover prior art, that may be disappointing, but just consider it a cost of doing business, drop the idea and go on. However, upon reasonably searching you don't discover prior art, then you'll gain confidence to move your invention forward. That's the way to go.

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