Patent Searching 101: A Patent Search Tutorial

Patent searching: A patent search tutorialInventors and entrepreneurs who are looking to cut costs frequently want to do their own patent search.  This is a wise first move, because patent searches are critically important. But inventors need to be careful.  It is quite common for inventors to do a patent search and find nothing even when there are things that could and would be found by a professional searcher.  So while it makes sense to do your own search first, be careful relying on your own search to justify spending the thousands of dollars you will need to spend to ultimately obtain a patent.  In other words, nothing in this article should be interpreted as me suggesting that inventors can or should forgo a professional patent search.  There is simply no comparison between a patent search done by an inventor and a patent search done by a professional searcher.

Having said that, every inventor should spend time searching and looking for two reasons: (1) spending time patent searching will familiarize you with the prior art; and (2) patent searches inform you on the prior art so you can focus on what makes your invention unique.  Of course, if you can find something that is too close on your own you save time and money and you can move on to whatever invention/project is next.

If you are going to do your own searching and find relevant patents you are going to need to learn some strategies, and also about the free tools that are available to you.  If you are going to do your own preliminary patent searching you will want to take a look at the United States Patent Office patent search page. A lot of information can be found free, and the system is not terribly difficult to use. There is also an excellent Help Section on the Patent Office website to educate inventors on how to use the online search features. There is also another excellent (and free) site that you should use when searching – Free Patents Online. Whenever I search tend to use Free Patents Online, simply because it is easier to access the patent illustrations. Which leads me to one of the best things about Free Patents Online — they provide copies of the actual PDF documents, which is why it is easier to obtain access to the images. Using the images on the USPTO website to obtain these full text PDF documents that contain the images is cumbersome to say the least.


Free Patents Online is also normally much faster than the USPTO site as well. Having said that, I sometimes find the patent search engine of the Patent Office better. Nevertheless, when I use the USPTO patent search engine  I go to Free Patents Online for the PDFs and to access related patents, which is much easier because everything at Free Patents Online is hyperlinked. So once you find a handful of relevant patents definitely go to FPO so you can easily jump back and forth and look at the patents that are cited in each relevant patent you find.  In other words, I suggest that you consider using the strengths of both the USPTO and Free Patents Online sites to make your searching easier.

Google also offers Google Patent Search, which is lightening fast (unlike the USPTO online database) even compared with Free Patents Online. The reason I don’t suggest this search tool first is because the Google Patent Search engine has some serious limitations. The number of fields that can be searched pales in comparison to the USPTO or Free Patents Online. Thus, if you are going to use Google Patent Search it is probably best used initially because when you start a search you want to cast a very wide net, so the limitations of the field search are probably not as important initially.  As you start to want to search for specific things, perhaps terms within a particular part of a patent or patent application, the Google tool is just not very useful.

Another thing you MUST know about when you use Google Patent Search is that there are also some holes in the database.  I have specifically looked for patents I know to exist and cannot always find them.  I have heard the same experience from other patent attorneys and patent agents.  Additionally, the most recent patents are not always available on Google.  What this means is you cannot only rely on Google, but you still must use Google.  The Google database covers patents that are issued all the way back to US Patent No. 1.  This scope is much broader than either Free Patents or the USPTO.  So while you might not find everything, while it is difficult to specifically narrow your search, you still really need to check yourself using the Google database to see if there are old references that might be on point.

When using the USPTO search features, either at the USPTO website or on Free Patents Online, one trick to improve search quality is to start by using the Advanced Search Page and searching in the specification field. Lets say, for example, you are looking for patents that relate to insulated containers for carrying beverages. In order to do this you will first need to pick a term or phrase that might appear within the written description of issued patents. Following this example, you might try in the search box – SPEC/”insulating beverage container”. When this search was conducted (on June 30, 2015) the results returned a list of 27 patents issued since 1976 that have used that phrase in the specification. This points to the first problem encountered by doing your own patent search online at the USPTO. You can only do full text searching back to 1976. This is probably not too much of a concern for those operating in the high-tech sector, but important to known nonetheless.  The fact that you can only search going back to 1976 can be extremely detrimental if you have a mechanical invention or gadget.  It is not at all uncommon — in fact it is extremely common — for inventors in every generation to seek solutions for the same or similar problems, which leads to the same or similar solutions/inventions.

In this case there are not many to choose from. Many times, however, the list will contain hundreds or even thousands of patents depending upon the popularity of the term or phrase selected. For example, if you search “SPEC/thermos”, you will find hundreds of patents that use this word in the specification. In fact, at the time this sample search was conducted (June 30, 2015) no fewer than 1144 US patents have the word “thermos” in the specification, and that is only for patents issued since 1976. So what should you do now? If you find too many patents, rework the specification field search. For example, if your search were “SPEC/thermos and SPEC/beverage” you get down to 241 US patents.  Ultimately, upon receiving manageable results, just click on several of the patents.  The key, however, is to start off broad and then narrow your way down to those that are the most likely relevant references.

Before going any further it is worth pointing out one major problem associated with inventors doing their own search. What you are doing, at least in the first instance, is a keyword search. Perhaps the reason there were only 27 issued US patents found that use the term “insulating beverage container” in the specification is because that isn’t the proper, or at least most common, way that patent attorneys and patent agents typically describe that particular feature set. This means it is essential to try a variety of different keywords in your search. I’ve done searches  myself using keywords in the past and haven’t been able to find anything when I knew there should be a universe of prior art to find. Once you stumble on the proper keyword combination the doorway starts to open.

Even with the best keyword combination the doorway only starts to open. To do a competent search you must do more. For example, once you receive manageable results you need to read the patents and see which ones are relevant. Always remember to try various search terms to make sure you are covering all possible descriptions of the invention. Along the way, as you read the patents and identify related ones keep track of the numbers and identify the US classification that relates to the type of invention you are searching. Upon identifying several US classifications that seem to relate to your invention, return to the Advanced Search Page and do a classification search.


For example, again following our example from above, you may notice that classification 206/545 seems relevant to the area of insulated beverage containers. As it turns out, this classification relates to special receptacles or packages with an insulating feature. See US Classes by Number & Title. Therefore, it would seem that patents within this classification are potentially highly relevant. So return to the Advanced Search Page text box and enter “CCL/206/545”.  This will search for all the patents classified in 206/545, which as of the time the search was conducted resulted in 156 US patents.  You can also add to a classification search to narrow.  For example, if you search “CCL/206/545 and SPEC/beverage”, you get down to 55 US patents issued since 1976.

Even as the old US classification system becomes obsolete the same will work with respect to the CPC classes. You would just use “CPC/” and the classification number without the numbers in parenthesis.

Admittedly, becoming familiar with the intricacies of doing a quality US patent search on your own will take time. Also, when searching using the USPTO system there are a number of fields that are searchable through the Advanced Search Page, which means that there are any number of ways to begin to tackle any search. If you are a serial inventor it is probably worthwhile spending time becoming acquainted with this and other ways to search. Having said this, however, if you are not intimately familiar with both advanced searching techniques and the classification systems, you are almost certainly going to miss what you are looking for in your own search. While it is advisable for every inventor to at least do a preliminary search on their own, it is not uncommon for inventors to do a search and find nothing. Every time I do a patent search I find patents that were findable in the Patent Office database, but not located by the inventor. Sometimes those patents are tangentially related, sometimes they are quite close and sometimes they are exactly what the customer has invented. This is no doubt caused by the fact that a patent search is akin to searching for a needle in a haystack.  That is why the best money you can spend is to hire a professional patent searcher.

Any successful search must use rely upon classification searching. While the classification system is helpful, never forget that patents are classified as the Patent Office sees fit. In order to identify the appropriate classification a broad search is necessary to make sure you familiarize yourself with how inventors and patent attorneys routinely characterize certain inventions, features, scientific principles and concepts. Only after you have a broad idea of all possible descriptions can you meaningfully search the classification systems. Having said this, let me acknowledge that some will disagree with this last statement. Frequently a patent classification search is the only type of search that is conducted by individuals who are professional patent searchers. It is important to realize, however, that a professional searcher only searches for a living and is far more familiar with the classification system than any inventor or even any patent attorney. I also want to point out that even if you think you are familiar enough with the classification system, you are not!


Take a look at this patent:

US Patent No. 6,619,810
Halloween treat carrier
Issued September 16, 2003

This invention, according to claim 1, is “a container having thereon a Halloween design, wherein the container and/or the Halloween design comprises a glow-in-the-dark material.” While this invention is outrageous and it is ridiculous that it was ever patented, that is not the point here. The point is with respect to the US classification for this patent. Prior to reading on, go to the US classification menu on the Patent Office website. Take some time and try and figure out what classification this invention would best be placed in. What you will find, I suspect, is that using the classification system in the first instance is at best cumbersome.

Now I invite you to review the patent. Notice that the US classification for this patent is 362/84 and 362/156. Notice that 362/84 is in bold. This means that it is the primary US classification for this invention. If you look at class 362 you learn that the class is broadly titled “Illumination.” The subclass of 84 relates to “Light source or light source support and luminescent material.” The secondary subclass of 156 a container, specifically a “bag, purse or trunk”. When looking at this particular invention in the first instance how many would have thought that this invention would best be described as a light source support and/or as an invention related to illumination? I doubt many would. Of course, when I asked the patent searcher I used this question, off the top of his head and without any preparation he named the classification immediately.

The point with this exercise, however, is to illustrate that finding a classification number first is difficult if not impossible when you are engaging in patent searches infrequently. It is always more wise to broadly search, perhaps searching the specification (using SPEC/) and find somewhat relevant patents. Then with respect to the most relevant patents, make note of their classification numbers and then search those numbers. The reason individual inventors do not find the most relevant patents is because they almost always fail to follow up the broad search with a classification search. In every patent search I can remember doing the most relevant patents were not discovered until I identified the most likely classifications and did a classification search.

Also remember that it is critically important to figure out what things are called.  I cannot stress this enough.  You need to use different names and labels.  You will find that patent attorneys typically call certain features by a select few names.  These names are not always obvious, but once you figure out what the industry calls something you are far more likely to find relevant patents.

If you feel you need the assistance of a patent attorney I can help. If you are interested in my assistance please send me an e-mail and we can discuss further about how I can assist you.

Good luck!


Warning & Disclaimer: The pages, articles and comments on do not constitute legal advice, nor do they create any attorney-client relationship. The articles published express the personal opinion and views of the author as of the time of publication and should not be attributed to the author’s employer, clients or the sponsors of

Join the Discussion

12 comments so far.

  • [Avatar for Gene Quinn]
    Gene Quinn
    July 25, 2015 02:13 pm


    You are absolutely correct to say that some patent attorneys still think they best serve their clients by keeping their head in the sand, not doing any kind of search, hiding or at least playing fast and loose with disclosure requirements under Rule 56. A bigger problem is also probably ridiculous claiming. It doesn’t lead to a meaningful First Office Action, and sometimes (perhaps frequently) leads to an inferior patent. The old saying — garbage in garbage out — comes to mind.


  • [Avatar for Andrea Walsh PhD JD]
    Andrea Walsh PhD JD
    July 25, 2015 12:31 pm

    Thank you so much for taking the time to address my inappropriate criticism. Your article is not the true source of my frustration when I read it, my initial thought was the inventor taking his/her search to a patent practitioner who is charging a 5 figure flat fee. The practitioner then asks a professional service for novelty patent search not to exceed a $500 before drafting claims, and never has a non-patent literature search performed, or discusses a supplemental examination after NOA , particularly when the inventor informs the attorney of relevant he uncovered.

    I give informational talks for inventors and entrepreneurs, small business owners, etc and patent attorneys still disregard the significance of relevant prior art for patent strength. These people do not know their options and their attorneys certainly are not educating them! I apologize for using this forum to take out my frustrustations.

  • [Avatar for Gene Quinn]
    Gene Quinn
    July 24, 2015 01:13 pm


    One more thing… You think I should point inventors to the USPTO as a resource and I failed to respond to that. If you actually read the article I do provide a link to various search pages on the USPTO website. I do not, however, point inventors to the basic information pages at the USPTO. Under the Obama Administration the USPTO has started to provide the public with bad advice, so I no longer recommend inventors consult the USPTO as a resource for accurate information. For example, the USPTO has started to advise that those who receive letters saying they infringe a patent should immediately reach out to the party sending the letter and that consulting an attorney is not necessary. If an attorney gave that advise it would be malpractice. Therefore, as a general rule, I don’t think inventors should rely on the USPTO as an honest broker for impartial information.


  • [Avatar for Gene Quinn]
    Gene Quinn
    July 24, 2015 01:09 pm


    I’m sorry you are disheartened, but it seems that your disillusionment comes as the result of unfamiliarity with independent inventors; perhaps even ignorance. What you and many other attorneys don’t seem to understand is that there is a limited amount of money available. People like you tend to think that every inventor will spend whatever it takes to obtain a patent. Sure, doing a worldwide patent search and a worldwide non-patent literature search is definitely best it is wholly unrealistic. Even major corporations with large budgets do not do a worldwide patent search and a worldwide NPL search prior to filing a patent application. I many instances large corporations and universities don’t do any search at all before they file, but if you are familiar with the industry you already know that, which makes your criticism all the more difficult to understand.

    Doing a reasonable search is better than doing no search at all. If you tell inventors that they need to spend $5,000 to $10,000 to do a search then no search will be done at all. I don’t understand why what is a difficult concept to understand.


  • [Avatar for Andrea Walsh PhD JD]
    Andrea Walsh PhD JD
    July 23, 2015 11:26 pm

    While the author provides adequate warning to the reader that as an attorney and searcher, he is not endorsing “that inventors can or should forgo a professional patent search”. He bases statement on this on the premise that “inventors and entrepreneurs do their own patent search to cut costs” and that “every inventor should spend time searching and looking … to familiarize themselves with the prior art”. Since I have always been a great admirer of Mr. Quinn, I am frustrated that the author did not refer the reader to USPTO Inventor ‘s Site which defines the importance of knowing relevant prior art-patent and non-patent literature as defined by AIA. As a regular reader and for the most part a supporter Mr. Quinn, I am disheartened that an opportunity to enlighten inventors/entrepreneurs that a perfunctory patent search even if done by a professional no longer adequate.

  • [Avatar for Anon]
    July 12, 2015 01:36 pm


    To be precise, the In re Hilmer doctrine was not over-ruled.

    Rather, it was made moot because the US changed their own internal rules. The doctrine is very much still alive since that doctrine aligns directly with the individual sovereign nature of patent law.

    Any “press” to the contrary simply suffers from a lack of understanding the nuanced nature of patent law. Here is a case where it matters very much from a legal standpoint of the means used to arrive at a “same ends.”

  • [Avatar for Paul F. Morgan]
    Paul F. Morgan
    July 12, 2015 11:34 am

    To explain Anon’s good point above, the AIA moved up the effective 102 and 103 dates of a U.S. published application or patent based on a foreign priority application [which is roughly 50% of all U.S. applications] to their FORIEGN filing dates. [Overruling the In re Hilmer doctrine.] A very significant change. Far more overall practical prior art impact than the AIA “first inventor to file” changes, since no Rule 131 declaration in many years has survived a challenge in patent litigation.

  • [Avatar for Paul F. Morgan]
    Paul F. Morgan
    July 12, 2015 11:14 am

    Gene, I am pleased to see that you keep emphasizing the importance of doing prior art searches before filing patent applications.
    Not doing so leads to more than just to wasted money, it leads to poorer quality specifications, unable to support distinguishing the prior art, needed claim amendments, etc. Yet several companies in the past stopped doing prior art searches before filing, to “save money” and for another reason – to get very broad claims when the examiner search missed the prior art, and to be able to assert or sue on those very broad claims [again with no prior art search] against the many companies that would pay to avoid litigation costs rather than challenge the validity of those claims in the requisite full blown litigation [through a jury trial and appeal] needed to do so. [Because successful S.J. on 102 or 103 is rare.] But that practice is now far more dangerous, given the likelihood of an IPR and/or attorney fee sanctions. [Not even to mention the new risk of a 101 rejection for claims so broad as to get treated as “abstract.”]

  • [Avatar for Anon]
    July 12, 2015 10:57 am

    To Itsik’s point, the AIA opened up a substantial avenue of prior art.

    Foreign language is just the tip of that iceberg.

  • [Avatar for Itzik]
    July 12, 2015 06:23 am

    And, of course, one should remember that there is land across the ocean. If you want to find material filed solely in Japan, for instance, consider searching espacenet. it is run by the European Patent Office, and includes patents and patent applications from all over the world, searchable in English. It also provides a very nice machine translation of full texts.

  • [Avatar for Benny]
    July 12, 2015 05:24 am

    A couple of notes:
    1 – regarding the statement ” every inventor should spend time searching and looking if for no other reason than to familiarize themselves with the prior art”, take into account that the prior art found in a patent database search is going to be at least 18 months old. If it is state of the art you are looking for, look elsewhere.
    2 – Allow me to share with you the results of a little test I performed – when searching for novelty destroying prior art to shoot down a competitors’ patent application, I found what I needed using Google patents. I then used keywords from the abstract of the patent I found in other databases – including one paid-for subscription service – and none of them returned that particular patent. (In Google it appeared in the sixth page of the results).

  • [Avatar for Arleen Zank]
    Arleen Zank
    July 11, 2015 11:42 am

    Since the USPC is now a static collection, searchers need to navigate the Cooperative Patent Classification scheme to find the newest patent and application prior art.