A patent search is when you research existing patents.

You can do a patent search using techniques like keywords, patent classifications, or both. Free and paid online tools that can help you find information and organize it. After a preliminary patent search, your attorney will help you do an even deeper search. That way, you won't miss any important information.

Your patent search may have one of the following goals:

  • To prove the novelty of an invention that you want to patent. An invention is novel if it has not been invented before. During a novelty patent search, you compare your invention with prior art. Prior art includes both patented and non-patented inventions that existed before yours. This is the most common type of patent search.
  • To get an overview of advancements in your field. This is called a state-of-the-art patent search.
  • To find out if an invention is infringing on an existing patent. This is called an infringement search and is usually done in connection with a lawsuit.
  • To find out if a patent is valid. A validity search compares a patent with preexisting patents. If the newer patent contains an invention that is too similar to one on a previous patent, the newer patent becomes invalid.

Regardless of the goal, there are techniques that can make your research faster and easier.

Why Is Patent Searching Important?

Patent searching is especially important for inventors who want to patent a new invention. Applying for a patent is expensive and time-consuming. If you submit an application to the United States Patent and Trademark Office (USPTO) without being reasonably sure that your invention meets the novelty requirement, you will have wasted a lot of time on an application that gets rejected.

An Overview of Patents

A patent is a property right that a government gives to an inventor. With a patent, the inventor can stop others from making, using, or selling an invention. In the United States, patents last for 20 years after the patent application is submitted, or for 17 years after the patent is approved. Other countries have different rules about patents.

Patents, trademarks, and copyrights, are part of intellectual property law.

For an invention to qualify for a patent, it must be novel, useful, and not obvious. There are three main types of patents:

  • Utility patents cover items that have a specific function.
  • Design patents cover decorative or ornamental parts of an item.
  • Plant patents cover newly discovered and newly invented plants.

A patent application is complex. It has to include claims, which say what parts of the invention the inventor wants the patent to protect. It must also have drawings and thorough descriptions of the invention.

Patent Search Tools

Free Search Tools

  • The USPTO database has tons of relevant information about US patents. It also has a Help Section that will guide you during your search. It has other valuable information as well, including a manual that explains the patent classification system. You might also want to check the USPTO's Official Gazette, a weekly publication that contains newly granted patents.
  • Free Patents Online gives you quick and easy access to PDFs of patents and applications. The documents are hyperlinked, which makes it a breeze to expand your search and compare patents.
  • Google Patent Search returns fast results and provides useful information about prior art. However, it may not have information about the newest patents.
  • Espacenet has a database with over 90 million patent documents from many different countries. One of the most convenient things about Espacenet is its translation feature, which is helpful if you're looking at patents from outside the U.S.
  • Orbit.com is geared toward design patent searches. Most other search sites focus primarily on utility patents.
  • Thomson Innovation offers search features and analytic tools to help you organize your search results. It also has a collaboration feature that will be useful if you are working with a team on your patent search.
  • Patbase is a database that has over 100 million patent-related documents. It is one of the most popular paid patent search tools.
  • The Derwent World Patent Index is a reputable global patent database that many companies put a high level of trust in.

Patent Search Tips and Techniques

Know Your Search Tools

Every patent database has different features that may help you. Go to the Advanced Search page and the Help Section so you can learn the ins and outs of any database you use. For example, you might use the Specification field in the advanced search to find patents with certain phrases in their specifications. A specification is the portion of a patent application that describes the invention.

Use Many Keywords

Search for keywords that aren't obvious. For example, you might want to patent a new type of toilet seat. Some patents may refer to toilets as "water closets" instead of toilets. Therefore, you should brainstorm any and all keywords that might relate to your search, and use all of them.

Using a large variety of keywords is important because some patents have language that is intentionally obscure. This is an attempt to "hide" the patent and can give the patent owner grounds for a later lawsuit.

The keywords you choose may relate to your invention's purpose, end result, or related products.

Learn the Classification System

Within the US patent system, inventions are divided into numbered classes and subclasses, each of which has a number. There are over 150,000 subclasses in the U.S.. By searching within your invention's class, you can narrow your search results. It takes time to become familiar with the classification system, and sometimes the class that an item falls into may surprise you. Most patent search engines allow you to search for patents within certain classes.

Europe and the U.S. share a classification system, but other countries use different systems. If you're interested in getting your invention patented internationally, you'll have to learn foreign classification systems.

Search by Patent Owner

If you know who your main business competitors are, search for patents that they own. You'll be able to see what they're doing and make comparisons to your own invention. It will also help you predict if your invention could become grounds for a possible infringement lawsuit.

Use Multiple Databases

Patent databases that you pay for access to often have smarter features than free search engines. They may generate keyword synonyms for you and automatically search for concepts that relate to your invention. You can compare what you find on the paid database to your information from your free searches.

Using multiple databases is important because some databases only go back a few decades. While older patents are no longer valid, older inventions are still considered prior art and may affect whether your invention qualifies for a patent.

Do a Citation Search

Patents often cite other patents. When you find a patent that relates to your invention, look up the patents it cites. This may lead to more inventions that are similar to yours.

Search by Example

Some search engines allow you to use a certain patent as an example. The engine will use information from that patent to come up with other relevant documents.

Cluster Your Search Results

Some search engines cluster groups of documents together according to a certain theme or concept. Some irrelevant items may sneak into your clusters, but this is a good way to get your research started.

Perform Boolean Searches

A Boolean search uses two or more keywords connected by a word like AND, OR, or NOT. Combine search phrases to help you find more relevant results.

Use Value Indicators

When a patent cites a previous patent, this is called a backward citation. The patented that was cited, therefore, has a forward citation. The more forward citations a patent has, the more likely it is that the patent will be relevant. Some search engines give you the number of forward citations that a patent has.

Look at Both Narrow and Broad Search Results

After you have found some relevant patent results using one search technique, "zoom out," and try another technique, broadening your search again. Looking at the search from a different angle can provide valuable information that you might have missed the first time.

Organize Your Results

Use charts and tables to help you keep track of what you find. Highlight the most relevant information. You can have handwritten notes as well as an electronic copy of all your compiled research.


Performing a patent search is a difficult task, especially if you've never done it before. The effort is worth it, though, because it will provide you with a base of information for your patent application. If you need help, you can post your questions or concern on UpCounsel's marketplace. The lawyers on UpCounsel have an average of 14 years of legal experience and come from schools such as Harvard Law and Yale Law.

After you finish your preliminary patent search, hire a professional searcher. He or she can help you sort through information. They many find important details you may have missed.