“Patent Prosecution” is a curious phrase for the non-initiated. The term refers to what happens after a patent application is filed with the U.S. Patent & Trademark Office (USPTO), particularly to the back-and-forth exchanges between the Patent Office and the applicant. These exchanges are generally referred to as an Office Action if initiated by the Patent Office, and a Reply when the applicant responds to the Office Action. The skill of the person drafting the Reply will usually be critical as to whether the application is issued into a patent or rejected. This article explains many aspects of patent prosecution and illustrates certain aspects thereof with current Patent Office data. This information should help patent applicants set reasonable expectations for their patent journey.

Once a non-provisional patent application is filed, the objective is to obtain the best patent possible while considering the specific situation. There can be many external factors outside of your control that can influence your patent journey, including who the patent examiner is, who the patent examiner’s supervisor is, what the current policies of the USPTO are, whether any landmarks court decisions have recently been issued, and whether another application covering aspects of your invention was filed just before yours. These factors are in addition to the internal factors such as the quality of your patent application. An experienced patent attorney can draft a high-quality patent application for an inventor, and often more importantly, guide a patent applicant through the patent prosecution.


Once a non-provisional patent application has been filed with the US Patent Office, your application is added to the queue of new patent applications. As of March 2021, the Patent Office Dashboard shows there are over 619,000 unexamined patent application waiting to be taken up by a patent examiner.

That number of applications seems daunting, but it is not uncommon for the US Patent Office action have a backlog of several hundred thousand applications.

As shown below, a patent application will typically stay in the unexamined application queue for about 17 months.

Unexamined Patent Applcation Inventory
Patent Application Timeline

Keep in mind, however, the17-month average is the global pendency average for all unexamined patent applications and therefore only tells part of the story.

The Patent Office has nine different “Technology Centers,” each separately managed, each tasked with examining distinct subject matter, and each containing one or more “Art Units.” An art unit is subgroup of patent examiners within a technology center (TC). Each art unit has a plurality of patent examiners, generally about 15–20, who are tasked to examine further subsets of subject matter under the TC umbrella.

It is important to know which technology center your application has been placed with because each TC operates a little differently than the others, particularly with respect to average pendency.

As shown in the chart below showing pendency from the TC level, the average time spent in the queue ranges from about 20 months (TC 2600) to about 27 months (TC 3700). The difference of half a year can feel significant to a patent applicant who was already waited over a year and a half.

Patents Pendency
Technology Center Subject Matter Examined Average Pendency before First Office Action (months)
1600 Biotechnology and Organic Chemistry 22.9
1700 Chemical and Materials Engineering 26.5
2100 Computer Architecture Software and Information Security 25.3
2400 Computer Networks, Multiplex, Cable and Cryptography/Security 22.3
2600 Communications 19.4
2800 Semiconductors, Electrical and Optical Systems and Components 21.4
2900 Designs 22.9
3600 Transportation, Electronic Commerce, Construction, Agriculture, Licensing and Review 25.6
3700 Mechanical Engineering, Manufacturing and Products 27.1

Finally, it’s worth mentioning that the US Patent Office provides a “First Office Action Estimator,” which is a software program that patent attorneys can access through their private Patent Office electronic portal. The Estimator provides an instantaneous answer; accordingly, once your application has been pending for over 18 months, and published, you can ask your patent attorney to inquire about the estimated first Office action.

What is an Office Action?

The Patent Office will not grant a patent unless the patent application satisfies all of the pertinent laws and regulations. In fact, instead of issuing a Notice of Allowance, the Patent Office will more likely issue a rejection letter, called an “Office action,” which is a transmission in writing setting forth the patent examiner’s reasons why your patent application does not satisfy the pertinent laws and regulations. The Office action should address each claim in the application and identify whether a claim is allowed, rejected, objected, and/or withdrawn from current consideration, and why the claim has acquired such a status.

Patent applicants have one opportunity as a matter of right to respond to the Office action. If the patent examiner is not satisfied with the applicant’s response and decides to maintain one or more of her rejections, then a second Office action, called a Final Office action, will be issued to explain why the application still fails to satisfy the pertinent laws and regulations.

47 months

Applicant can again revise their application and file a reply to the Final Office action asking the Patent Examiner to reconsider a rejection. But such reconsideration is granted at the Examiner’s discretion (i.e., she is not required to enter the application revisions).

If a reply filed after a Final Office action is not entered by the examiner, then the applicant will need to refile the reply with a Request for Continued Examination (RCE) and pay the associated fee. This transaction guarantees the reconsideration of your application, including the amendments and arguments proposed in the reply filed “after final.”

Depending on the various factors mentioned above, a patent application may be subject to a large number of Office actions and patent prosecution can go on for years. As shown in the USPTO dashboard below, the average pendency for an application having at least one RCE is 47 months.

Ultimately, a patent application will be allowed to issue as a patent or will go abandoned when the applicant gives up for one reason or another.

The back-and-forth exchanges between the applicant and the patent examiner is called patent prosecution. A patent attorney with years of experience working with the Patent Office can advise you about how to prepare and file responses to an Office action.


Most applications – about 86% – receive at least one Office action from the USPTO setting forth some issue with the application that must be addressed before the claimed invention will be allowed to grant. As such, only 14% of applications are allowed after their initial review.

It is certainly satisfying to receive an early Notice of Allowance from the Patent Office, but sometimes the resulting patent will be considered stronger if there are one or more rejections in the record. Consider this from the perspective of an investor: if the patent was granted without issue, one often questions how well the patent examiner’s search and examination was carried out. By contrast, when a patent examiner issues an Office action that rejects your claims over relevant prior art, and the claims are then amended to be allowable, one may assume the claims to be stronger because they are as broad as the prior art allows and narrow enough to not include the prior art.



As noted above, the patent examiner who is tasked with examining your application is a critical factor. There are currently over 8,100 patent examiners at the USPTO, as shown in the dashboard graphic below.

The sheer number of examiners in the graphic should indicate that vast variety of skillsets possessed by each individual examiner. Some examiners have years of experience and some have very little experience. Some examiners were trained during an era of Patent Office history known for “patent quality,” which means they were encouraged to reject patent applications. Other examiners were trained during an era known for less quality and faster reduction of the backlog, and they may be more inclined to allow an application. To be clear, the corps of patent examiners is not monolithic. Sometimes specific patent prosecution strategies must be developed for certain patent examiners.


The U.S. Patent Office administers a Registration Examination for individuals seeking to practice before the USPTO. One does not need to be an attorney to prepare, file, and prosecute a patent application on behalf of another. But the Patent Office has traditionally required an applicant for registration to have a technical degree or background.

The passage rate for the Registration Examination is typically about 50%. If one passes the Exam and earns a Registration Number and they are not an attorney-at-law, then they are considered a Patent Agent. On the other hand, if an attorney-at-law passes the Exam and earns a Reg. No., they are deemed a Patent Attorney.


A good patent attorney has familiarity and experience with the patent examination processes as carried out by the Patent Office. Establishing working relationships with the patent examiners, carrying out examiner “interviews” to discuss the merits of a claim rejection or to explore options for patentability, focusing on the dispositive issues, and revising claim language that leads to an allowance are examples of certain skills and tools relied on be a patent attorney. The knowledge, skills, and experience required to be successful at the Patent Office are unlikely to be possessed by everyone, including every person with a Registration Number.

A patent attorney is not necessarily an expert in the specific area of technology that your invention or patent application is directed to. Thus, it should be understood that a collaborative inventor-patent attorney relationship is required to prepare a patent application and prosecute it before the Patent Office. The inventor usually possesses the specific knowledge needed to describe and distinguish the invention from other inventions in the field, and the patent attorney should possess the specific knowledge needed to translate the technical information into a simple argument the patent examiner will understand.

Patent Prosecution

One way to think about why you need a patent attorney is to consider the success rate for applicants who prepare, file, and prosecute their own patent applications. Such do-it-yourselfers are referred to as “pro se applicants,” and the Patent Office recognizes their need for assistance and indeed offers assistance to pro se applicants. Nevertheless, the Patent Office employees are limited by ethical rules and can only do so much for a pro se applicant. Ultimately, the quality of the patent application will determine its fate.

Unfortunately, the Patent Office does not publicly release statistics specific to the success of pro se applicants. But data can be obtained via the Freedom of Information Act, and such information has been obtained in the past. In an article analyzing such data, the author found pro se applicants to have very low success rates compared to patent applications linked to a patent practitioner. For example, the author found that 76% of applications filed by pro se applicants go abandoned compared to 35% of applications filed by patent practitioners. The data therefore highlights what should be obvious: working with a patent attorney will significantly improve your chances of earning a patent grant.


In his 16 years combined as a patent examiner and a patent attorney, Jason M. Nolan has guided hundreds of patent applications through the process to obtain an issued patent. Don't allow your application to be dragged through the mud, schedule a free consultation to see how Nolan IP Law can help you obtain a patent.

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