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Patent Simple – Conducting a Patentability Search

A patentability search involves searching the prior art, which includes published patent applications, issued patents, and any other published documents, with the aim of determining whether filing your patent application makes sense. If you find prior art that describes your invention completely or renders it obvious, you probably shouldn't bother trying to patent your invention. A patentability search is sometimes called a prior art search or simply just a patent search.

In this article, we discuss a useful strategy for conducting a patentability search.

Where to start your patentability search

Each patent office has its own online searching tool allowing you to search through that office's published patent applications and patents.

When doing your own patentability search you might be inclined to start at your home country's patent office. This would be a mistake. Or, you might decide to begin your patentability search at the USPTO, since this is the largest single national collection of patents and published applications in the world. This would be a better start and is a very common approach, but it is also a mistake.

The best place to begin a patentability search is at the EPO. Why? Because the EPO houses the largest freely accessible collection of patents and published applications from in the world, covering all major patent granting authorities, the US included. You see, this is the first lesson of conducting a patentability search: the prior art knows no bounds. A 1962 patent from East Germany is prior art, just as much as a US published patent application from 2007 is. So, it makes sense to begin your patentability search at the patent office that has the most prior art.

Now you head off to the EPO search page and begin typing in keywords. This would be a good start, but there's something you should know first–patent classifications will save you days of time and also save you the heartache of prosecuting a patent application in vain.

The USPTO has a good, detailed classification system, if a little difficult to navigate. The WIPO has a coarser classification system that is used worldwide, known as the International Patent Classification (IPC) system. You may be tempted to use one of these to begin your patentability search. However, consider for a moment that the European Classification (ECLA) system is a stroke of brilliance. Taking the best of both worlds, the ECLA system combines the detail of the US system with the universality of the IPC system. The ECLA system uses IPC symbols as a framework onto which further detailed sub-symbols are appended. This means that if you know the ECLA classification symbol, you also know the IPC symbol. Not all patents or published patent applications have an ECLA symbol. However, those that do have had their ECLA symbols assigned by European patent examiners, who are world renowned for their search skills.

You should start your patentability search by finding the ECLA classification that best fits your invention. If looking at pages of classification symbols seems daunting, then you can try a shortcut. Use the keyword search to find a few relevant patents or published patent applications, and then look at their ECLA symbols. Just type in some simple keywords and scan the results until you see something that looks similar to your invention. Then, note the European classification symbols. Then head back to the classification schedule and see how these classifications are described. In a sense you're testing the waters to see how European patent examiners use the system. After a few iterations, you'll find your magic symbol.

Now you can use your ECLA symbol to search, adding keywords to further reduce the count of search results. Remember to keep your keywords generic or combine them with the OR operation. Use wildcards to include plural forms of words. Further narrow your result count by using the AND operator. ECLA symbols can be combined in this manner as well, if your invention has two essential aspects. Ideally you want to narrow your initial patentability search to somewhere in the neighborhood of 20-50 documents. This is not so many that you have to spend days reading them, but no so few to make you wonder if you've missed a big one.

Read (or at least skim) each patent or published application and decide whether it discloses some or all of your invention. If you find one that discloses your entire invention, then your patentability search has come to an unfortunate (but at least speedy) end. Your invention is not novel and therefore cannot be patented. If, on the other hand, you find a patent or published application that discloses part of your invention (but lacks one or more key components or features), then place that document aside for future reference (and future citation in an information disclosure statement, or IDS, if you file a US non-provisional patent application). Discard any document that lacks most key components or features of your invention.

Look at the key documents and check for other ECLA symbols you may have overlooked. Repeat your initial patentability search by focusing on any new symbols.

Beginning your patentability search with a combined ECLA symbol/keyword search is aimed at quickly finding the most relevant documents. However, there are two significant limitations. First, the EPO offers a weaker advanced search tool than do the USPTO or paid-access databases. This is partially compensated for by the detailed nature of the ECLA system and by selecting good keywords, but it is still not as robust as other advanced search tools. Second and more important, not all documents have an ECLA symbol. Only those patents or published patent applications that have been touched by an EPO patent examiner do. While you can conduct a worldwide patentability search using ECLA symbols, you cannot find everything.

Refining your patentability search – Finding everything else

There are five paths to digging up more prior art: searching IPC symbols, searching other databases, searching key inventors and companies, reviewing references, and plain old Googling. Ideally, you'll want to try all of them.

If you've just finished the ECLA leg of your patentability search, then why not hang out at the EPO search site for a little while longer and try some IPC symbols. To get an IPC symbol, simply drop the final letter in an ECLA symbol. If your ECLA symbol ends in a number, then you already have your IPC symbol. You'll get many more hits with your IPC symbols than you did with your ECLA symbols. You can adjust for this by combining your keywords with AND or by using narrower keywords. You may have learned some new keywords based on the documents you've already found, such as more accurate component names, inventor names, and applicant (company) names. Use these during the IPC leg of your patentability search to trim the number of results down to a manageable number.

Your patentability search can also be continued using other databases. If you only pick one other database, use the USPTO. The advanced search is excellent and you can use your IPC symbols. You can also make a foray into the US classification system. It seems arcane at first, but it's richly detailed. There are numerous pay-access databases around, and some, such as Delphion, offer reasonably cheap day passes. Most commercial databases offer collections in the same league as the EPO and offer very advanced search tools as well.

An essential refinement for your patentability search is to search key inventor names and applicant (termed assignee in the US) names. You may have discovered some key people or companies during the first part of your patentability search. Both the EPO and USPTO search tools allow you to search by inventor or company. You can relax your other keywords and even relax your classification symbols, depending on the uniqueness of the names searched. Prolific inventors and companies are excellent search beacons.

After you've got a good stack of prior art patents and published applications, you'll want to look at the forward and backward references. Forward references are patents or applications that cite or reference the document in question. Backward references are any documents that are cited or referenced by the document in question. Forward and backward references exist because many patent offices require the applicant or inventor to identify the most relevant documents. In the US, you are required to cite any relevant prior art documents when filing for a patent. In Europe, you are often required to mention the closest single document right in the text of your patent specification. In the US, as well, many inventors talk about the prior art in their "Background" section and specifically mention old patents or other prior art documents there. For search purposes, those are backward references. Forward and backward references are like a fishing net, where each knot represents a patent. In a patentability search, you want to find the knot that is most like your invention. Start at a knot that is near your invention and follow the lines. You may find something closer.

On US patents, the references cited (backward references) are listed on the first page. For US applications, you'll have to check Public PAIR. The EPO search results often list cited references and offer a link to view forward references. Search reports (usually European or PCT) also contain backward references.

Reviewing the forward and backward references usually turns up more prior art, and sometimes the most relevant prior art.

Lastly, it never hurts to type some of your essential keywords into Google. Suppose you find an inventor who got a patent on something similar to your invention. Typing her name into Google might turn up an article describing a prototype she built. These kinds of documents, which are called non-patent literature, are often perfectly acceptable prior art. Each patent office has its own rules as to what kind of non-patent literature qualifies as prior art. But if you find a technically sound article related to your invention or documentation indicating that someone has constructed something similar to your invention, these will likely be considered prior art. The USPTO has even cited the Bible as prior art.

When to stop your patentability search

You will find the above method for conducting a patentability search requires some iteration. You may find a classification symbol, which leads to a key inventor, which leads to another classification symbol. Search long enough and you'll keep seeing the same documents pop up from time to time.

The 80/20 rule definitely applies. In the first 20% of the time you spend searching, you'll find 80% of the relevant prior art patents and published patent applications. In the remaining 80% of the time, you'll find the other 20% of the documents. Diminishing returns is the name of the game. When you keep seeing the same documents over and over, it's probably time to call it quits. If you follow the above method for conducting your patentability search, you'll have matched the search quality of the EPO examiners and beaten most of the USPTO examiners.

Always keep in the back of your mind the reason for doing your patentability search. You're trying to find your invention in the prior art as fast as possible. Yes, it's disheartening when you are "successful," but on the bright side, this will save you massive amounts of time and money trying to re-patent the wheel. If it's beginning to look like your invention is novel and not obvious, then you'll have to judge for yourself when you've "failed" in your patentability search and when it's time to begin filing your own patent application.

If the above seems daunting and you decide to use a patent search service, ask them about their search strategy. Ensure they use more than just keywords and make sure they understand your invention. The last thing you want is to spend hundreds or even thousands of dollars engaging a patent search service only to receive a stack of unrelated patents in return.

Copyright © 2009 R. Smith