What Is Prior Art Search?

A Prior Art Search identifies products, inventions, and concepts analogous to an idea intended for patent registration or manufacturing.

Prior art is an invention that is similar to your invention, that existed before yours did. So if you have an idea for an invention, or if you've already created the invention, you need to do a prior art search. The prior art search will turn up any inventions that are similar to yours. Patent application examiners often reject applications because there is prior art for that idea.

Why Is Prior Art Search Important?

Think of a patent as a monopoly that the government gives you on your idea. That means you're the one who came up with it, and invested the time and money into developing it. To get this monopoly, your idea has to be totally original. You can't know your idea is original without looking for similar ideas.

Prior art searches aim to

  • Prove your idea is new and original
  • Know how your idea fits in the technological field
  • Check patents other people in your field are filing
  • Look out for people who might someday infringe on your idea
  • Look for inventions that you might accidentally infringe on if you make and sell your invention
  • Find out how strong your idea is

You should do a prior art search before you develop your idea. Use the internet to do your search. Know that investors and companies you might work with will do a prior art search, too. If you find prior art, you shouldn't ignore it. Investing in research and development is costly, which is why prior art searches are essential business practices.

Different Forms of Prior Art

Prior art searches are important before you get a patent or manufacture new technology. The prior art doesn't have to be something that you can buy in the store. Prior art is anything that shows someone came up with a similar idea to yours previously. Even if you hear about businesses who do research and development without doing prior art searches, you should not skip a prior art search.

Prior art doesn't just mean inventions that are extremely similar. For instance, if you invent a five-wheeled car, your prior art isn't just five-wheeled cars. Four-wheeled cars are prior art, too, because they're similar enough. To make your five-wheeled car a patentable invention, you have to show why it's more original than just putting an extra wheel on a four-wheeled car.

Your invention could be represented in lots of prior art. If each part of your invention exists in different pieces of prior art, then you probably won't get a patent, either. You want at least one portion of your invention to be completely new. A prior art search actually helps you with that.

Searching for Prior Art

A Patentability Search

If you find prior art, it can help you with your invention. Finding prior art in a patent search can give you ideas to make your idea truly original. Seeing what already exists will help you make yours different.

If you want to get a patent, you need to know if your idea qualifies as patentable. It needs to be:

  • Original
  • Useful
  • "Non-Obvious" when compared to the prior art (think back to adding a fifth wheel to a car)

A Clearance Search ("Freedom-to-Operate")

Clearance searches find patents that might get in the way of you commercially producing or selling your product. You're looking to make sure you don't infringe on someone else's rights when you sell your product. This kind of search usually happens in the country (the jurisdiction) where you want to sell your invention.

Freedom-to-Operate searches are important if you want to sell your product. You could have a patent on something, and still violate someone else's patent or right to sell a product.

How does this happen? If you invent an improvement on an existing process, you can get a patent for that. But you can't actually sell anything to do with that existing process. Someone else owns those rights. You need their permission first.

A Validity Search

You do a validity search to determine whether prior art existed when a patent application was filed. This is often done to show that a patent held by a competitor is invalid and should be revoked.

A Landscape Search

In this kind of search, the term landscape refers to a technological field. You do a landscape search to find trends, to see how many patents are being filed, to learn what competitors are doing, and to stay up-to-date with a technological field.

Getting Professional Help

Doing all this research on your own is daunting and difficult. That's why some people hire a professional to conduct a patent search for them. The professional could be a lawyer or someone who works in the Patent Office.

You can also hire information specialists to do prior art searches in other databases, the internet, and offline. This is called "non-patent literature."

Many inventors who intend to manufacture and sell their ideas work for businesses, or own businesses. Hiring someone is a significant investment of money. The search results that a professional can produce, however, are more detailed than what you can do on your own.

Before you put any money into professional searches, do searches on your own. If you find prior art, then you don't need a professional to tell you it exists. Work on your idea to make it more original first.

Searching on Your Own

You can conduct a very comprehensive search by yourself if you invest the time. Before you start, you need to learn about search techniques. Finding prior art is all about understanding how to search and where to search. You have to do two separate searches to finish a prior art search. You need to do a patent search and a product search.

Your prior art search could find prior art in just a few minutes. You need to spend a long time exhausting all search avenues. What you want to do is find evidence that your idea is not original. If you can't do that, then you might have an original idea on your hands. Assume, however, that if you can't find prior art, you haven't looked hard enough. That's why continuing to look, even while you develop your idea, is important.

Make sure you keep everything you find that relates to your idea. You want thorough records of your prior art search.

Use the Internet to Research the Market

Prior art is ideas that are similar to yours. Competing art is ideas that solve the problem you're trying to solve. Come up with keywords that describe your invention. Your first step is to conduct an internet search.

The keywords you use to search for prior art are very important. Think of keywords that describe your idea. Start with the most obvious ones first, because they might turn up millions of search results which you won't be able to search through. Use more specific search terms so you can sort through the search results.

While you look through your initial search results, you'll probably find words that describe what you want your idea to do. If you don't have experience in the field, you wouldn't have known to search these words before. Now that you've found them, search for them, too. Your first searches will help you find good keywords to describe your idea.

Be aware of any emerging or new terms that describe ideas like yours, or ideas in your field.

Non-Patent Literature includes:

  • Scientific journals
  • Academic papers
  • Dictionaries
  • Videos
  • Blogs
  • Product journals
  • Books

Obsolete and In-Development Products

Historical records are important when you look for other products. An old product might have existed in the past that counts as prior art. So you need to search both modern and historical records.

Find out what kind of products are in development. Just because something isn't finished doesn't mean it's not prior art. Searching academic research will also give you information about products that are starting development.

Search Offline

Go to the library and the bookstore. Check magazines in the field. You could find information that wasn't available online.

You should also talk to people in the field who have seen a lot of products. That means suppliers, vendors, or retailers. They may have seen something like your idea pass through their supply chain or shop. Retirees from the field are good sources of information for products that are older, and that might not be in use anymore.

Do a Patent Search

Patents contain information that is very important to your prior art search. Internet searches, database searches, and academic resources won't contain the information your patent search finds.

The patent search will probably be more useful than the product search. That doesn't mean you can skip the product search. But there are lots of ideas with patents that nobody ever put on the market. Your patent search is more likely to have results, even if your product search did not.

A patent search will find

  • Details about how inventions work that won't be on the internet
  • Up-to-date information about other inventions
  • Information about who owns which technology and inventions
  • Inventor and assignee-based results
  • Patent citations within other patents

You have to find all the patents that are similar to your invention. You also have to know which parts of each patent are the most important regarding your idea.

Just like you will continue to conduct internet searches, you also need to continue to conduct patent searches. You could find work that inspires you to make your idea more original. You could also find people who might be good partners or collaborators. This also identifies your latest competition.

How to Search With Concepts, Classifications, and Keywords

Concepts are how you describe your invention. If you wrote a bunch of descriptions of the same thing, these descriptions would share concepts. You want to conduct searches with these concepts. Within each concept, you come up with keywords.

Keep in mind: concepts and keywords don't work for everything. You can't describe everything with concept words. The same concept words, for example, could apply to very different gene sequences. It would be hard to use a concept or a keyword to look for genetic patents. Classes and sub-classes would be more helpful here.


Patents are organized into class and sub-class. These classes and sub-classes describe types of inventions. They come with symbols in numbers and letters. You can use the classification symbols when you're searching, so use any classifications that might be relevant to your idea. Check the database of classifications to get started.

Sometimes the primary classification for an invention similar to yours isn't what you'd expect. US Patent No. 6,619,810 is a lighted Halloween bag that carries candy. Its classification is first in lighting, and then secondarily in bags. If you're searching for bags, it might take you a long time to get to this patent.

Read the Patents

When you find relevant patents, reading them will give you several advantages

  • The "Claims Section" gives you what the invention is supposed to do
  • You'll get an idea of how patents are written so you can write your application
  • You'll understand the difference between a patented invention and something saleable

Patent Search Resources From WIPO

The World Intellectual Property Organization is a good resource for inventors. If you're hoping to get a patent or sell your intellectual property, WIPO is a good place to go. WIPO offers great patent search resources:

WIPO offers some specific search techniques that will help you conduct a prior art search using esp@cenet®. In the example, you want to invent something that will block cell phones from getting or sending communication in an area like a room.

In the example, WIPO offers examples of concepts: "mobile phone, noise, public room, prevent."

Each concept has keywords that go with it: "cellular phone, disturb, silence, public, etc."

You can try searching combinations of these words. Do it by putting "and" between each word (even between concepts with two words, like mobile phone.) If you conduct a few searches on the esp@cenet® database, patents come up. You then look through the patent for the classification symbol. When you have it, include it in your search.

WIPO's example yields several existing patents:

  • US2001006886
  • WO0207120
  • EP1061686
  • WO9818232

All of these patents have something to do with preventing mobile phones from working in specific spots. Even a quick search example turns up prior art results. It's not close to being a full search, but it is a good illustration of how prior art searches can work.

Keep Watch

Set up permanent search alerts. In between your manual searches, you can have search engines and databases continuously looking for your keywords. You'll receive an e-mail or an alert when new information is published.

Adjust these search terms and alerts whenever you find new information. If you encounter a new keyword or move into a new area of research, change your search parameters.

Your prior art search is ongoing, but it shouldn't consume you. What you want is to get an idea of what's out there already. You won't ever be able to find all the prior art.

Google Patent Search Can Help

In 2015, Google released Google Patent Search. This search feature combines patent searching and prior art searching. The point is to make it easier for people doing patent and prior art searches to get to relevant material. With hundreds of thousands of patents filed each year, patent searches are overwhelming. The Google Patent Search feature is useful both to businesses and individuals who might have little or no experience with patents.

Four main features make Google Patent Search useful:

  • The search interface. This interface puts prior art and patent searches together. Instead of basing search criteria on the kind of language that's in patents, Google makes it easier on users. They divide results in ways more similar to how search engines do it.
  • Google Scholar. Along with patents and prior art, Google Scholar adds academic writing to the search. The Google Scholar database now uses Cooperative Patent Classifications (CPC.) The classification system helps keep patent descriptions standard through the U.S. and Europe.
  • The results you get from your search will be in groups. The groups will focus on different themes; this helps searchers see patterns. The groups help people find technology information without having to understand how to interpret a patent.
  • Google Translate will help turn up results that are in other languages. Your keywords, translated, might match with a French patent, for example.

If you're interested, you can discuss your search results if you click the "Discuss" button on the Google Patent Search page.

Google used to have two separate pages, one for patent searching and one for prior art searching. In 2012, Google's patent search was incorporated into regular search results. You selected a tab to search for patents. The 2015 version stands on its own.

Google searches patents from other countries, not just the U.S. Google has also operated a space where they were buying patents online.

Though Google Patent Search is very fast, especially compared to other databases like Free Patents Online, it has problems.

  • Both USPTO and Free Patents Online offer more search fields than Google Patents
  • Google Patents Search is a good starting point, but it is less effective when you start to narrow your search
  • Google Patents Search isn't as helpful if you're searching for terms in parts of patents or applications
  • The Google Patents Search has gaps in its database because you can only search full texts back to 1976

Professional Search Techniques

Professionals and companies who deal with intellectual property (IP) have different techniques for searching prior art. Article One Partners created a list of how different IP professionals search for prior art. These techniques are helpful when you conduct your own prior art search.

Intellogist deals with patent research. This company recommends a 10-step prior art search. They recommend starting with broad search terms and narrowing from there. The sixth step has some important information on how to search. It says that you should keep searching with new terms. You should also search different places.

United States Patent and Trademark Office (USPTO) offers a seven-step search. This is the way their employees do prior art and patent searches. You classify, look at full-text, and then review. Reviewing your results is the most important step. Not Just Patents has an annotated version of the seven-step search.

European Patent Office has a three-step search process. This search distinguishes between product searches and patent searches. They also talk about searching for products that aren't used anymore. Get pointers on how to search for mentions of products that are not in use, like using periodicals and other techniques outside of patent databases.

Linux Foundation's search process is six steps. The Linux Foundation's process is a good way to look up information about the field and the existing technology. You start by organizing what they call your background information before you actually look for prior art.

Sagacious Research has a six-part search. They offer a course called Intellectual Property Rights & IP Services, and their search techniques are in that course.

How Prior Art Searches Fit With Lawsuits

If you aren't seeking a patent, you may still need to do a prior art search. If you manufacture something that you didn't know is already patented, you're still infringing on that patent holder's rights. You're not allowed to manufacture their idea without their permission.

If someone sues you because they think you infringed on their patent, a prior art search can help. You can conduct a prior art search to try to invalidate their patent. If their patent is found invalid, then they don't have grounds to sue you for infringing on their patent.

Your prior art search is your evidence when you want to invalidate a patent. You'd show this either to the Patent Office or in court during a lawsuit.

Patent holders who are suing for patent infringement also do prior art searches. That way they can avoid surprises if their opponent produces evidence of prior art.

In many places, new patents are open to people opposing them for a certain amount of time. Prior art searches are one of the ways people oppose new patents. You don't have to be suing someone (or being sued) to oppose a new patent.

Get Legal Assistance

A competent patent attorney will have search resources and experience that you don't. Post your patent search needs here or other legal need and receive free custom quotes instantly from the top 5% of lawyers. UpCounsel screens lawyers to provide you with the people who can help you with your prior art search.