What Is a Patent Citation?

Rich Goldstein

Founder & Principal Patent Attorney

Patent citations can be important as you prepare patent applications to protect your intellectual property or if you are researching and want to learn patent data.

What Is a Patent Citation?

A patent citation is any important document or research paper cited by a patent applicant, patent examiner, or third party that relates to the content of a patent application. Truly any publicly available patent documents can form the basis of a patent citation analysis. Here are some typical types of patent citations:

  • Existing patent applications
  • Existing patents;
  • Journal articles;
  • A research paper;
  • Publications on the internet;
  • Trade show disclosures; 
  • Conference abstracts. 

Types of Patent Citations 

There are two main types of patent citations:

  1. Backward citations; and
  2. Frontward citations. 

Backward Citations

Backward citations are patent documents that have been published and are publicly available prior to the filing date of the patent application that the citation is cited on. These can also be referred to as “prior art.” Prior art or backward citations are ideally all of the patent data that is available to the public before the date a patent is filed. 

A stack of books

Prior art can be helpful to learn about the background scientific literature and patents related to an underlying patent. If you want to research patent data about a topic or group of related patents, prior art is a great supplemental resource once you have conducted some initial keyword and classification-based searches.

Patent examiners that review patents for approval or rejections also add their own prior art to patent applications. Patent citations made by the patent examiner are classified according to the relevance to the patent application they are cited on. 

This means the patent examiner’s backward citations can be very helpful in understanding what the Patent Office considers the most relevant prior art for any given patent. 

It can be very helpful to review the backward citations and any scientific literature for not just a specific patent that you are interested in, but also any related patent family member. This is because each patent application in a patent family may be reviewed by a different patent examiner. Depending on the patent examiner assigned to the patent application, he or she may have a different idea of which prior art is related to the underlying patent.

Forward Citations

Forward citations, on the other hand, are patent documents that have been recently published that have cited the underlying patent application. Thus, once a patent application has been filed, it may then be cited by journals, research paper, new patent applications, and the like. These would be classified as a forward citation.

A forward citation is often used by competitors or those in related industries to the underlying patent system. They can provide insight and data into the current state of the field within the specific industry.

This includes understanding the direction that a particular market might be heading, keeping abreast of the current trends, and understanding what a competitor is focused on. Thus, a forward citation is especially good for business intelligence purposes.

A forward citation can aid in understanding potential licensing opportunities in your field, areas where patent infringement might be taking place, or areas where a market could be expanding or closing. 

Keep in mind that older patent applications and patents will have many more forward patent citations than newer patents and patent applications. This means it is important to explore a range of related patents when conducting searches and patent citation analysis.

Why Patents Are Cited

The underlying reasoning for why patents are cited as either a backward citation or forward citation is because of their relationship to and similarity with the applicable patent application.

Patent applicants cite prior art, or a backward citation, in their applications. This lets the patent examiner know they have considered the applicable patents and believe their patent is distinguishable.

Patent examiners conduct thorough patent searches on their own with every patent application. Therefore, there is no way to escape a similar patent that may stand in your way. By citing the similar patent as a backward citation, this signals to your patent examiner that you have seen the related patent and can demonstrate that your patent application is distinguishable.

When a patent is cited, it also indicates that the examiner knew about this particular patent and still considered your invention patentable. Then your patent will be presumed to be valid over the cited patent.  So if your patent is later involved in litigation, it would hard for the other side to claim that if the examiner only about this patent, they would not have granted the patent.

Two persons pointing to a sheet of paper

On the other side of the coin, patent examiners will often cite a backward citation in a patent application as justification and support for their decision to reject a patent for approval. Patent examiners take their job seriously and will conduct very thorough prior art searches in reviewing a patent application. Moreover, different patent examiners will focus on different related patents.  This underscores the importance of conducting a detailed and robust patent search as you draft a patent application. 

Patent citations can be important. Patents that are often cited by other patents tend to have more economic value than patents that are not cited by others. Patents that are often cited by other patents gain more visibility in their respective fields, which can be helpful in presenting additional business opportunities and industry recognition. 

Why Patent Citations Are Helpful

Patent citations can be very helpful from a business perspective. Specifically, patents can:

  • Determine what competing companies are developing; 
  • Determine the direction of a specific technology or field; 
  • Offer comparisons to advances made by competing companies; 
  • Showcase popular technology of the time; and
  • Alert you to similar patents and ideas you made have. 

Patent Applications

Patents are a form of intellectual property rights. They give the patent holder the right to exclude others from making, using, selling, or importing whatever is within the scope of the patent. The United States Patent and Trademark Office is the government agency that administers intellectual property patents and makes patent determinations.

The patent application process is extensive and complicated. Patent applications can be rejected if a patent examiner determines a patent is too similar to a prior invention or intellectual property.. This is why patent searches are so important to conduct up front, even before you take steps to submit your patent application to the Patent Office. 

Patent citations can be helpful tools as you conduct your patent searches during the applications process. 

Patents as Business Tools

Even if you are not submitting a patent application yourself for a specific invention or intellectual property, patents and patent applications can contain very helpful data from a business perspective. Patents can contain important insight into the business direction of a company, including the inventions they consider valuable, the specific technology or product they will be pursuing, and other important business details. 

Problems With Using Patent Citations

Patent searches using other citations can lead to incredibly helpful data. However, it is important to keep in mind that a patent application or resulting patent may not list every applicable or related patent.

The patent citation list for any given patent may leave off some very important related patents by virtue of the type of technology or product the underlying patent is as well as the specific patent examiner assigned to the patent. 

Some patent examiners can fixate on a specific string of prior art while ignoring a different area or field that is still highly relevant. This is why even though patent citations are helpful resources, they are not the only resources when looking to exhaust a specific area, technology, or field of interest. 

Patent Citation Searches

Patent citation searching can be a complicated process. However, to gain valuable business insight, it can be very helpful in the long run to learn tips and tricks to best pinpoint the types of patents you want to find.

You can conduct your patent search within the United States Patent and Trademark Office’s various patent databases. Conducting this patent search before you submit your application will save you substantial time and money in case your idea has already been developed. 

The United States Patent and Trademark Office has a great video that walks through a step-by-step strategy for conducting a patent search. Here are some of our own tips.

Patent Citation Searches 

If you want to conduct your own patent citation search, you will want to make sure to cover a range of databases. This will allow you to make sure you have covered all ground and have found all the potentially relevant hits. Patent searches can take some time but can provide powerful business intelligence and resources as you prepare your own patent application. 

Person typing on a laptop

Searching The USPTO Database

The United States Patent and Trademark Office, also called the USPTO, has specific patent databases. Here are a few pointers for searching them for patent citations:

  • Learn boolean search operators, i.e., you can combine search terms using AND, NOT, and OR; 
  • Understand abbreviations used by the USPTO and incorporate them into your search;
  • Keep detailed notes about the search terms you used and the dates you conducted your search; 
  • Search within a patent citation’s family and view the citations made within the related patents. 

How to Draft Patent Citations

Patent citations can be tricky. If you are looking to draft a patent application and need to cite other patents, here are some tips and tricks to write the best patent citations that will be accepted by the United State Patent and Trademark Office. 

Patent citations are short and follow a specific format. There is no specifically applicable style guide to follow in drafting your patent citations. This means you can pick which citation format is most familiar to you. From there, you just need to make sure each and everyone of your citations follows the same format. 

Here are some examples:

  • APA, i.e., American Psychological Association Style
    • Format: Name of 1st Inventor, Name of 2nd Inventor; Add more as needed. (Year Patent Issued). Patent number. Source for Patent. 
    • Example: Smith, Robert, Schull, Nancy. (2010) U.S. Patent No. 8,442,278. Washington, DC: U.S. Patent and Trademark Office.
  • Chicago Manual of Style
  • Format: name of 1st Inventor, Name of 2nd Inventor; Add more as needed; Patent title. Patent number, date of patent filing, and issue.
  • Example: Robert D. Smith, Patent for Important Technology. U.S. Patent D656,012, filed August 18, 2012, and issued January 07, 2014.
  • National Library of Medicine (NLM) Style
    • Format: name of 1st Inventor, Name of 2nd Inventor; Add more as needed, Patent title. Country Patent document type (simply type patent for U.S. other countries may list different types) ISO country code Patent number. Issue date. Pagination by p (optional). Physical description (optional). Int. Cl. International Classification Code (optional) ISO Country Classification Code Cl. (optional) Appl. No. Application number (optional); Application filing date (optional). Language (if not English). International Company, LLC, assignee (Central, CH), Weight loss device, and method. United States patent U.S. 2,381,521. 1977 Nov 10. Int. Cl. A42F 5/00 (20030204); A61B 19/00 (20030204); A32C 016278 (). Appl. No. 05/224,047; 1979 Nov 10.

Related Questions

Where Can I Find Patent Citations?

You can find patent citations and all citation information exclusively in the USPTO database also contains the citation information. Visit the USPTO database, and in the left column, click on “patents”, then on “search patents.” As you do your research, you should visit this site and mark the date you regularly visit, as more citations are added every day.

What Is Not Considered A Patent Citation?

Any non-patent literature such as the following is not considered patent citations:

  • Technical standard
  • Athecnical cientific material
  • Conference Proceedings
  • Research reports
  • Clinical trials
  • Technical reports
  • Books or manual

Can I Cite Copyright As a Citation?

You can still cite copyright and other copyrighted materials in your patent granting process. However, you must get permission from the copyright owners before you use, copy or change any copyrighted material.

Is it Time to Protect Your Ideas?

Book your FREE Idea Protection Strategy Call

Join over 10,000 others who have asked us to help protect their best ideas and inventions.

Do You Have Intellectual Property (IP) You Need To Protect?

Your FREE Strategy Call is a pressure-free, no obligation way to get all your questions answered.
Goldstein Patent Law patiently listens to you, and then explains your options so you don’t lose your rights.
Call (718) 701-0700 or use the form below to secure your complimentary strategy call now.

By clicking Schedule Now, you agree to our Privacy Policy, including our Cookie Use.

No Obligation. Completely Confidential.


We're Social

Is it Time to Protect Your Ideas?

Book your FREE Idea Protection Strategy Call

Join over 10,000 others who have asked us to help protect their ideas.