Free Inventors Help, Information and Resources

How to Search Patents

"Concern for man and his fate must always form the chief interest of all technical endeavors. Never forget this in the midst of your diagrams and equations."

Albert Einstein
 Below you will find the 7-Step U. S. Patent search strategy provided by the United States Patent and Trademark Office.

 This is a very good place to begin your search. Please keep in mind that there are many variables, (perhaps a patent already exist for an invention similar to your idea but has a different name or description).
We strongly recommend that you consult with a registered patent attorney or patent agent, (see finding an attorney) or at very least talk with someone who has been through the process.

The 7-Step U. S. Patent Search Strategy - Quick Start

Patent and Trademark Depository Library (PTDL) staff are available to provide
training on U.S. patent search processes and research tools including the
Cassis DVD-ROM system, the PubWEST database, and the USPTO website .


1. Brainstorm keywords related to the purpose, use and composition of the invention.

2. Look up the words in the Index to the U.S. Patent Classification to find potential class/subclasses.

3. Verify the relevancy of the class/subclasses by using the Classification Schedule in the Manual of Classification

4. Read the Classification Definitions to verify the scope of the subclasses and note see also references.

Access Full-Text

5. Search the Issued Patents and the Published databases by
"Current US Classification" and access full-text patents and Published

Review and References

6. Review the claims, specifications and drawings of documents retrieved for relevancy.

7. Check all references and note the U.S. Cl. and Field of Search areas for additional class/subclasses to search
Official Website of the
United States Patent and Trademark Office

The article below is re-printed courtesy of  Jack Lander
Copyright © Jack Lander,

About The Patent Search

Why the patent search?

The patenting process should always be preceded by a patent search. There are three main purposes for the search:

  • To determine if your invention is already patented.
  • To discover similar inventions that will affect how your patent is written.
  • To avoid costly legal amendments if a patent that affects your patent application is found after you file.

In order to get a patent on your invention it must be novel, and it must be "unobvious to one skilled in the art." Any invention that is known to exist, or known to have existed in the past, is considered prior art. It doesn't matter whether such invention was patented or not. If it was public information at any time, past or present, you cannot claim it as your invention, and you cannot patent it.

By "unobvious" we mean that if you make an improvement on a product that already exists, your improvement should be sufficiently novel that it would not have been obvious to the designers of that product. For example: Suppose that you create a wire shape that rests on your collarbone, and holds a cell phone so that you can talk "hands off." A patent examiner would probably say that the manufacturers of cell phones no doubt have already had this idea because it is an obvious accessory even though it is not being manufactured. It does not pass the test of unobviousness to one skilled in the art -- the art, in this case, being cell phone designing and manufacturing.

So, one of the three main reasons for the typical patent search is to discover if your invention is already patented, or is an obvious improvement, and therefore not novel. But consider this: A patent search is only one aspect of prior art. Unpatented inventions, which make up the bulk of products sold in large chain stores, may also be prior art. Even a written article in a periodical, or a display at a trade show, if discovered, will be used to argue against the novelty of your invention.

Now, when you have a patent search made, the searcher will send you copies of patents that affect the novelty of your invention. Sometimes one of these patents will be exactly like your invention. More often, these patents will define inventions that accomplish the same or a similar purpose is a way that, hopefully, is significantly different than yours. Again, the copies of existing patents that you will receive are only one kind of prior art, but usually the dominant kind that determines whether or not you can get a patent. Busy patent examiners (at the U.S. Patent & Trademark Office) don't usually search every periodical throughout all history to see if your invention is described in one of them.

Thus, you might wonder if there is a more comprehensive search than a typical patent search. The answer is yes. You can order a more complete search, but the cost is generally too high for most independent inventors. It is usually cheaper to assume that the typical search is a good enough basis for writing your patent application, and if the patent examiner finds prior art, either in the form of an issued patent or an article in a periodical, your patent attorney or patent agent can amend your application at less expense than the cost of an initial comprehensive search.

Is a patent search required?

No. There is no patent regulation that insists on it. But it is foolish to proceed without it unless you are a researcher in a certain field, and you already have expert knowledge of the prior art in that field. To file for a patent without knowing what, in effect, is your competition, places the entire burden of the search on the patent examiner at the Patent Office. The patent examiner will, of course, find the same patents that your searcher would have found. But this could cause a bit of resentment by the examiner because you were too lazy to do your homework. And that resentment might show up as critical rejection of many or all of your claims. A patent application that presents the obvious prior art, and makes sound arguments as to why your invention is different, has a much better chance of going through smoothly.

Who can do a patent search?

Anyone. You can do it yourself. I have done six paper searches, three at the Patent Office in Washington, DC, one at the New York Public Library (patent branch), one at a university, and one in a branch Patent Depository Library. I have also done a few less complete searches on the Internet.

Searching is not difficult. Every patent has a class and subclass number, which is similar, in effect, to the Dewey Decimal System used by our libraries. Once you find the class and subclass numbers, which you can find by examining a few patents on inventions that are similar to your invention, you can do an exhaustive search. If you search at any of the depositories, such as I mentioned above, you will find a large index book that is arranged alphabetically by name, and you can locate the appropriate class and subclass easily.

If you search the Internet, by going to, you will find many ways to locate pertinent patents. Try it, and you'll be amazed. And you will have demystified the process so that you can deal more confidently with the professional who does your search. Be aware, however, that presently at the Patent Office web site you won't be able to locate patents prior to 1976 unless you know their patent numbers. Thus, for most inventions we are missing essential prior art. A professional searcher, using the paper index, does not have this limitation.

Should you engage a professional searcher?

I highly recommend it. Professional searchers are far more proficient than we amateurs. After all of the searching I've done, and the reading about how professional searchers work, I've come to the conclusion that a search is best done by the professional searcher. If you miss an important patent when you do your own search, the cost in time and money is significant -- sometimes heartbreaking. I speak from experience.

How do you find a professional searcher?

There are two main ways: 1) have your patent attorney or patent agent handle the search for you; 2) find a searcher in the ads in Inventors' Digest magazine, and engage the searcher yourself. (Subscribe at 1-800-838-8808) And there is a third way: If you use me as your mentor, I will give you the name of the fellow I use for my own searches. He has thirty years of experience, and he is affiliated with a patent attorney who provides a patent ability opinion free. (No catch. He hopes to get your patent writing business, of course.)

If your patent attorney or patent agent handles the search, he or she will hire a professional, and will usually mark up the price because of the handling. Also, he or she will want to present you with a patentability opinion, and this will be an additional charge -- generally a total of $500 to $1000. A search alone, if you hire the searcher directly, will usually cost $250.

A patent search without a patentability opinion is like going to the doctor for a checkup, and not having the doctor tell you the results. This opinion can be self-serving (for the opinion writer), and you are dependent on the ethics of the patent professional. Just as a doctor might advise a costly medical procedure because it makes him money, and not because it is essential, a patent professional can advise you to file knowing that if you are granted a patent it will not have any "teeth" in it -- that is, it will be a relatively weak patent. Interview the attorney or agent before hiring him or her, and make sure you feel a sense of trust.

About patent examiners.

Patent examiners, in a sense, are like judges. They sit in a neutral position between the public and the inventor. They have an obligation to the public not to grant an inventor the rights of a patent on items that belong in the public domain. But they also have the obligation to encourage innovation by granting legitimate rights to inventors. And they are nice people, not ogres. If you visit the Patent Office, now located in Alexandria, Virginia, you can visit the examiner who will handle your eventual application. I was amazed at how friendly these people were. However, if you have employed a patent agent or attorney to prosecute your patent application, the examiner will only offer advice or answer questions pertinent to your application to the attorney. If you file your own application, you not only can get advice from the examiner, he or she will write at least one claim for you if you wish.

A final caution.

One patent attorney in my area does his own searching on the Internet. Two of my clients who engaged this attorney to write their patent application had their applications rejected because of prior art that this attorney did not find. (They sued the attorney, and got their fees returned.) Be sure that however your search is done the searcher will search the entire patent files -- that is, before 1976 as well as after. In my opinion, patent attorneys and patent agents should stick to writing, and delegate the search to a professional.

 Copyright © Jack Lander,

Google's Beta Patent Search
You may want to try Google's Beta Patent Search

Tell Me More About Patents
Return to Our Home Page

 Free Inventors Help Icon   Home Page

 Free Inventors Help Icon   Where do I begin? (the basics)

 Free Inventors Help Icon   What is a patent?

 Free Inventors Help Icon   How do I search patents?

 Free Inventors Help Icon   How do I apply for a patent?

 Free Inventors Help Icon   How do I find an attorney?

 Free Inventors Help Icon   Prototypes and Prototypers

 Free Inventors Help Icon   What is an industrial designer?

 Free Inventors Help Icon   How do I market my invention?

 Free Inventors Help Icon   Invention Links for Kids

 Free Inventors Help Icon   Books for Inventors

 Free Inventors Help Icon   Licensing Your Invention

 Free Inventors Help Icon   Inventor Friendly Resources

 Free Inventors Help Icon   Inventor Stories

 Free Inventors Help Icon   Inventor Organizations and Clubs

 Free Inventors Help Icon   Our Sponsors

 Free Inventors Help Icon   Helpful Inventor Links

 Free Inventors Help Icon   Invention Investors and Angels

 Free Inventors Help Icon   How to Avoid Scams

Page Updated January 16, 2023