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How to do a Prior Art Search

The basics on how to start and conduct a prior art or patent search to find out if an invention is novel and non-obvious. By Carson Patents, USPTO Registered Patent Agent, Gregory Carson.

Prior Art and Patentability Searching Basics.

The patenting prior art searching basics from a patent search firm. How to start and conduct a prior art or patent search.

A prior art or patent search is conducted to identify the prior art for an invention. The novel and non-obvious elements of a patentability study are determined for an invention based on its prior art. The prior art search is an essential first step on the steps to patenting. Professional patent practitioner help is highly recommended to evaluate whether an invention is novel and non-obvious.

Searching is basic research.

A basic patent search (prior art search) is researching various data sources. It is determining if there is prior art that discloses your invention. Prior art includes existing patents, patent applications, and non-patent literature. It can be found anywhere around the world. Prior art is any existing documents that show or describe the invention. However, it can also be things that are similar. Anything that describes how to make and use an invention is prior art.

In other words, a prior art search is research looking to find a disclosure of your invention. This is important because, a disclosed invention is no longer novel. A consequence of not being novel, is that the invention is not patentable. Therefore, no patent will be allowed, or issued, if the invention is already disclosed.

Important Tip: An inventor has 12 months from the date of public disclosure of an invention to file a claim for a patent. In other words, a disclosed invention is its own prior art 12 months after it is disclosed to the public.

The things needed to do a search.

There are three basic elements of input for the search engines. To do a patenting prior art search, you will need the following three things:


The place to start a patent search is with the description of the invention. A description of the invention that is just a simple sentence or two is the easiest to work with. A concise description is easier to work with. This is because what you will need for actual searching in databases is just the right few keywords. And, then, the right classification(s). When searching, look for any existing products and processes that are similar to the invention.


The description is used to develop a good set of keywords. Then, the keywords are the words that are used for database searching. The best keywords to use are those terms and phrases about the invention and its field of use that describe it most accurately and completely. When searching, a good concise description is simpler and easier to use than a long explanatory one. Further, the concise description likely already has most of the keywords needed to start and do a search. In addition, too many synonyms can become confusing.


The final piece of input for a patent search is the classification search. You need to do a classification search. In other words, you need to search the various classifications that the invention is likely to be put in. The classification system to use is the CPC Scheme (CPC website). The CPC is the Cooperative Patent Classification system. The CPC (like all classification systems) categorizes inventions into classes. The idea, then, is that all the other inventions that are like an invention will be in the same class(es). Thus, searching the likely classes is essential to a good patent search.

Important TIP: If you don’t know or can’t find the class(es) for your invention, one easy place to start is the class(es) of similar patents found when searching. First, find similar prior art. Then, use that classification as a starting point for the new invention.

The following data sources, is a minimum list of places to search. The more places searched the more complete the search. However, the following list of sources will give you a good start. And, quite likely, more prior art (existing stuff like yours) than you were expecting. In order to have a good basic search, these databases represent the minimum list of places to search. There are specialty patent search firms. Be careful to verify credentials.

  • United States Patent and Trademark Office (USPTO) –
  • European Patent Office (EPO) –
  • World Intellectual Property Organization (WIPO) –
  • Google Patents –

Additionally, it is important to search the internet generally. In other words, a prior art search includes searching with a regular search engine search too.

The steps to doing the searching.

There are 3 basic steps for starting and conducting a patent search. This is a basic method for starting a prior art search. It is conducting a database search for an invention. For example, enter keywords or classifications as search input. Then, review the list of search results.

Search Step 1: Keyword searching in one place.

Step one is to use the keywords to search. The easiest databases to search in are the Espacenet, and Google Patents databases. Pick just one to start with. Enter keywords into the search entry text box. Look for products or processes that are similar to or describe your invention. Read the abstract and claims. If it mentions things that are close, read deeper into the document. Additionally, for potentially relevant items that are found, be sure to download copies for later reference and study.

Search Step 2: Refine the keywords, and add classification searching.

After, the initial search. Step two is to review the results. Read the collected prior art. Then, assess, evaluate, and refine keywords, phrases, and classification(s) to narrow the results. Look for those products or processes that are similar to the invention. The more specific the keywords and phrases, the better the search results will be.

Search step 2 includes a classification search. Where an invention has several likely classes, it is best to search them all. Searching by class is just entering the class into the search engines and reviewing the results for prior art. Use the classes from the prior art if the invention is not more formally classified.

Search Step 3: Search all of the places (data sources).

After reading and refining keywords and classifications, the third search step is to search all data sources (places) to be searched. An exhaustive search includes databases from many countries in many languages. There are over 100 searchable datasources. Prior art can come from anywhere. At a minimum, the databases listed above should be searched. In other words, this is a basic patent prior art search, a more complete search includes searching in related areas and searching into more data sources.

Important TIP. Proper searching is essential to good patent specification writing. Searching guides good claim writing by finding existing similar claims. Well written claims improve the protection the patent provides.

Patent Practitioner Help Recommended.

The United States has specific criteria. Whether a patent, patent application, or other disclosure may be relevant prior art can get complex. For example, in certain circumstances, an earlier disclosure by the same inventor may be excusable, or prior art. In other circumstances, an application filed earlier, but published later than your application, may be cited against your application. 

Patenting is complex.

Prior art searching and patentability determinations are time consuming and complex tasks. Additionally, all patents, patent applications, and non patent literature from around the world need to be examined and considered in an exhaustive search. An exhaustive search includes searching in other related fields. Other related fields are areas of potential use or related technologies that may be applicable.

Help is available.

If you are unsure, book a Free Initial Consultation to discuss the available options. Contact Carson Patents firm for prior art searching. Start the steps to patenting for your invention.

Disclaimer: Nothing in this article constitutes legal advice.

Contact Carson Patents Firm to start a patent prior art search for your invention.