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Patent Prosecution: An Analysis

Aehahini N

19 Jun 2022

Patent Prosecution Decides the Fate of a Patent Application

Prosecution is the term used in the field of law to describe the plaintiff's side of a litigation. Patent prosecution, on the other hand, is the process of drafting and filing a patent application, as well as obtaining patent protection through the patent office. Patent prosecution differs significantly from litigation. The phrase is frequently misunderstood by those unfamiliar with patent terminology. If you need a lawyer to sue someone for infringing on your patent rights, you should hire a patent litigator. A patent prosecutor, on the other hand, is someone who can assist you in developing an intellectual property protection strategy, including preparing and filing patent applications with the patent office.

Patent litigators do not need a technical background or to be licenced to practise before the patent office. Patent prosecution attorneys must have both a law licence and a licence to practise before the patent office. A patent agent must not only prepare and file a high-quality patent application, but also skillfully and articulately advocate for his client's invention's patentability before the patent office reviewing the application. This is referred to as "patent prosecution." The patent agent must provide a courteous response to the patent examiner's objections and rejections in the office action once the patent examiner has studied the pending patent application and written an office action. The patent agent must describe the distinctions between the invention and the examiner's prior art in the response.

According to WIPO, “In addition to preparing and filing a high-quality patent application, a patent drafter filing in a country that requires substantive examination must skillfully and articulately advocate the patentability of their client’s invention before the patent office reviewing the application. This process of review is called patent prosecution”.

For many patent offices, the time between filing a patent application and obtaining a first office action is at least two years. Following the applicant's completion of the appropriate filing procedures, most patent applications in most patent office’s experience a protracted period of inactivity, however the application will eventually be evaluated by a patent examiner. Any prior art identified by the applicant will be taken into account by the patent examiner, who will normally do his own search of the prior art and compare it to the claims in the application.

Most patent offices organize their examiners into groups based on technical expertise. These groups' examiners are tasked with reviewing a large number of patent applications for closely related ideas. Not unexpectedly, these examiners become well-versed on the previous art in their field. Some patent offices even provide examiners with access to prior art libraries that are specifically tailored to their technical competence. Of course, patent examiners usually have engineering degrees in fields related to the technical fields of the patent applications they assess. Many patent examiners have extensive degrees in science and engineering, and some even have legal training.

An examiner's prior art does not always represent the oldest, best, or even most original technical disclosure. The patent examiner is under no obligation to locate the earliest teaching on a technological subject. All he has to do is locate a prior-to-the-effective-date disclosure that reveals the innovation the applicant is attempting to claim. It's not uncommon for an examiner to come across a favourite piece of prior art that he references again in the applications he examines. Examiners frequently cite previous patents and published applications as relevant prior art, but they may also cite technical publications, books, treatises, and other sources.

From country to country, the effective date of prior art that can be used against a pending application differs. The majority of countries use a "first-to-file" method. In such countries, any technical disclosure made public merely one day prior to the filing of an application, including the applicant's own public disclosure, is considered relevant prior art. The component of such systems that requires "non-disclosure before filing" is called as a "absolute novelty" requirement. In other words, in order to qualify for patent protection, the applicants' initial public disclosure of an invention (without a confidentiality agreement in place) must be to the relevant patent office.

The definition of "absolute novelty" varies by country, so even if the patent agent learns that his client has publicly disclosed his invention without a confidentiality agreement in place, he should check to see if the facts of the disclosure fall under one of the exceptions to the "absolute novelty" requirement. In some nations with an absolute novelty requirement, for example, inventions whose operation cannot be determined from a public disclosure are an exception to the requirement, and the invention may still be patentable.

Several other countries, including the United States, have "first to invent" systems. An inventor is legally defined as the first individual to conceive of an idea and put it into reality in a "first to invent" system. Prior public disclosure of an invention prior to the filing of a patent application becomes less important in such a system (since the focus is on the conception date), and "first to invent" regimes typically do not require "absolute novelty" prior to the filing of a patent application but instead provide a grace period for the inventor (who has already conceived of the invention prior to its public disclosure).

Accordingly, the inventor may choose to publicly disclose his innovation before filing his patent application. Any technical revelation made public previous to the filing of the application may be cited as prior art in such nations, but the inventor will be given a time period to demonstrate that he completed his invention prior to the public disclosure claimed against him. In addition, most first-to-invent systems impose an absolute time limit for filing a patent application once the invention is publicly disclosed. In the United States, for example, the absolute time limit for submitting an application following the first public publication is one year. This big obstacle prevents an inventor from filing a patent application many years after the invention was made. Similarly, such first-to-invent patent systems impose an absolute time limit on the inventor's ability to demonstrate that the invention was completed before the previous art alleged against him was disclosed. In the United States, both barring events have a one-year time limit. One of the reasons for these restrictions is the amount of effort required to administer such a system. Remember that, unlike first-to-invent systems, first-to-file systems often do not provide for a grace period, thus an invention could be time barred by any publication or patent application made prior to filing, including the inventor's own.

When a patent application is filed prior to one's own, it becomes relevant prior art when it is published or issued as a patent. Even though the application was not made public until after the filing of the pending application, the effective date of such applications/patents as prior art dates will be their filing date, not their publication or issue date. On January 1, 2005, A submits a patent application to the EPO. On November 1, 2005, B submits a patent application. According to EPO standards, A's patent application is published on July 7, 2006. Even though A's patent application was not published until after B's patent application was filed, A's patent application is prior art to B's patent application. In other words, the filing date, not the publishing date, is the effective date of A's application. However, according to EPO rules, A's published application can only be referenced against B's application for the purpose of eliminating novelty. (Note that this applies to A's patent application as "prior art" to B's patent application and is a separate consideration from "priority of invention" if A and B's patent claims are similar.)

In first-to-invent systems, priority of invention arises when it is necessary to ascertain which of two or more inventors thought their respective discoveries first, because only one of them can acquire a patent for it. The EPO is not a first-to-invent jurisdiction, as previously stated.)

1. Responding to office actions:

After reviewing a pending application, a patent examiner will issue a "office action," which is also known as a "official action," "official communication," or "examination report." The government's official position on a pending patent application is represented by an office action. From the applicant's title to the length of the abstract, the office action may address practically any part of the application. The most essential sections of the office action deal with the fundamental issues surrounding the patentability of the pending claims. When an office action arrives, the patent agent should notify his client as soon as possible and explain the patent office's conclusions to him.

The examiner may question if the specification contains enough information for an ordinary person skilled in the art to comprehend and practise the invention as claimed — these are known as "enablement" rejections. The examiner may also wonder if the specification has enough information about a feature mentioned in the claims. The patent agent can counter these rejections by demonstrating where the allegedly missing subject matter is actually disclosed in the specification, arguing that the missing subject matter was sufficiently known in the prior art that its disclosure was not required for enablement, and/or amending the pending claims to remove this missing subject matter.

The examiner will almost always have conducted a review of the prior art and will typically find prior art that arguably reads on the claims. (This term means that the prior art is within the scope of the claims in the application as they are presently drafted.) If the examiner finds a single piece of prior art that reads on one of the claims, the examiner will reject the pending claim as having been “anticipated” by the prior art. If the examiner finds that a combination of references in the prior art together disclose the claimed invention and that a person of ordinary skill in the art would have been motivated to combine these references, the examiner will reject the pending claim as being “obvious” over the prior art. In some jurisdictions “obviousness” is known as “lack of inventive step.” The patent agent can rebut these rejections by doing one or more of the following:

a) Arguing that the examiner has misunderstood the cited reference(s);

b) Arguing that the examiner has misunderstood the applicant’s invention and/or the pending claims;

c) Arguing that the references cited by the examiner cannot properly (legally) be combined, and/or

d) Amending the pending claims so that they recite an invention not disclosed in the cited references.

2. Drafting responses:

The patent agent’s reply to an office action is known as a “response.” In the response, the patent agent must fully answer (respond to) all the examiner’s comments regarding the application in the office action. If the patent agent does not respond to all the rejections made by the examiner, the patent agent’s response will likely be considered “non-responsive” and not further considered by the patent examiner. A patent agent must always strive to file a complete response to an office action, as a non-responsive office action response can seriously impair the client’s rights. The patent agent will want to provide his draft response to the office action to his client and should explain the office action to him. The patent agent’s client may be extremely knowledgeable in the field of the invention and may be able to identify distinctions between the prior art cited by the examiner and the invention described in the pending patent application and/or the pending claims. Also, there are often choices to be made in making claim amendments – amendments which typically add narrowing limitations – and the patent agent should give his client the opportunity to make these choices. The client may know better than the patent agent which choice of claim limitations will still allow the claims to retain commercial significance.

3. Getting claims allowed:

The patent examiner will review the patent agent’s response to the office action. Frequently, the patent examiner will conduct a supplemental search for pertinent prior art. The patent agent will often respond to the patent examiner’s first office action by pointing out that either the prior art cited by the examiner is inappropriate for a set of very specific reasons and/or the patent agent will argue for the patentability of a feature that the examiner did not notice or appreciate in the claims as originally filed.

Consequently, the examiner may decide to conduct a supplemental search for pertinent prior art in preparing the next office action. The patent examiner may not find the patent agent’s response persuasive either in light of newly-found prior art or in view of the prior art originally cited. Patent examiners are typically trained to read the pending patent claims in their broadest reasonable interpretation: such procedures result in having more rather than less prior art to read on the claims. If the examiner is not persuaded that the claims are patentable – giving the claims their broadest reasonable interpretation in view of the prior art – then he will issue another office action that explains the reasons he cannot allow the application and/or the claims in their present form.

The Interview

Many patent office’s allow patent agents and inventors to speak with the patent examiner about the pending application. This process is known as an “interview” with the examiner. Because official business will be discussed, both parties may be required to submit complete and accurate written descriptions of the interview, these records typically becoming part of the file history for the patent application. In preparing for the interview with the patent examiner, the patent agent should thoroughly review the office action and the prior art cited, and be ready to explain to the patent examiner in clear, concise and persuasive language why the pending claims are patentable over the prior art. The patent agent may want to prepare some possible additional claim amendments and share these with the patent examiner.

For example, if the patent examiner and the patent agent can work out a set of acceptable claim amendments during the interview, the review process can be successfully concluded. During the interview the patent agent may learn that the examiner has been interpreting the prior art cited in a different way, or with a different nuance, from the interpretation of the patent agent and his client. Once the patent agent fully understands how the examiner sees the prior art, the former is in an excellent position either to: 1) educate the examiner about the prior art (if the examiner has misinterpreted the prior art) or 2) see more clearly what range of claim amendments would put the application in condition for allowance.

In some countries, the patent agent is permitted to bring the inventor to the interview and many patent examiners find comments and explanations made by the inventors to be very persuasive. Of course, the patent agent will want to counsel the inventor before the interview. Patent examiners are not typically allowed to conduct interviews prior to the issuance of the first office action but they may conduct interviews thereafter.

Responding to a Second Office Action

As mentioned above, the patent examiner may issue a second office action. The patent agent will need to prepare and file a response to the second office action. The second and subsequent office actions should, hopefully, involve a narrower set of issues than the first office action. Additionally, if the second office action involves some of the prior art cited in the first office action, the patent agent should be able to complete the second office action response much more quickly than he completed the first office action response.

The process of office action and response may be repeated until either the patent examiner agrees to allow the applicant’s pending claims or until the applicant decides that no meaningful claim coverage can be obtained and he abandons the application. For financial/administration reasons many patent offices do not allow the office action/response cycle to continue too many times before additional payment of fees is required.

Final Office Action

The potential for additional payment of fees is sometimes signalled by a “final” office action. As noted previously, the world’s patent offices often operate differently with respect to the specific procedural aspects of patent prosecution. In US practice, the response to a final office action requires that the application either be placed in condition for allowance, appealed or abandoned. In responses to final office actions, patent examiners will not typically entertain the applicant’s further arguments regarding the prior art.

Basically, the pending claims need to be amended to place them in an allowable condition based upon the patent examiner’s comments. If the applicant disagrees with the patent examiner’s characterization or the prior art or the patent examiner’s interpretation of the patent claims, he may appeal the patent examiner’s opinion. The patent examiner will sometimes allow some claims while rejecting others. The patent examiner may also merely object to some claims because they depend on a rejected base claim. In such situations the patent agent can obtain a patent for his client by cancelling the rejected claims and then allowing a patent to issue on the claims that have not been rejected. The patent agent could even file a continuation (or divisional application) containing the rejected claims and continue to argue for their patentability in a subsequent case. Deciding whether to take the claims allowed by the examiner rather than continuing to fight is a strategic decision that must be made by the client after appropriate counselling from the patent agent.


The final office action will have a deadline for response. Again, the specific procedural requirements of the world’s patent office’s vary. In the US this deadline is six months, with the first three months not requiring the payment of an extension fee. The patent agent may file a response to the final office action. The patent examiner will review the response and issue either a “notice of allowance” or an “advisory action,” which is typically a short one-page form in which the examiner states his objections to the application. The patent agent may even prepare and submit one or more supplemental responses to the patent examiner in view of the advisory action. However, the patent agent must understand that the application goes abandoned on a certain date and that all prosecution must be completed by that date. If, for example, a patent agent in the US submits his reply to a final office extremely close to the six-month deadline date (e.g. on the last day), then it is highly unlikely that the examiner will even review the response before the six-month deadline arises, in which case the patent application will simply go abandoned. This is because, as noted above, unlike filing a response in a non-final office action, the filing of a response in a final office action does not itself satisfy the deadline requirements. The only actions that actually stop the deadline are:

1) having the examiner issue a notice of allowance; 2) having the examiner issue a new, nonfinal office action; 3) abandoning the application; 4) re-filing the application as some form of continuing application; 5) filing a notice of appeal.

Consequently, the patent agent must closely watch the dates related to final office actions. Even when the patent agent files a timely response to a final office action (e.g. within three months), the application can still go abandoned if one of the four actions above has not transpired. Thus, in some instances the patent agent may need to take additional steps to keep a patent application pending just because he has not received a reply from the patent office (even when the response that he filed, if reviewed, would have placed the application in condition for allowance).


In responding to a final office action, the patent agent typically prepares a formal response and if the examiner does not find the response persuasive, the patent agent can either file an appeal or some form of continuing application (usually known as a “divisional” application outside the US). An appeal typically involves review of the patent application by a board comprising several senior patent examiners. Most of the world’s patent offices provide some form of appeal for decisions made by individual patent examiners. The specific procedures followed in appeals vary from country to country. In the US, the patent agent first submits a document known as an “appeal brief” and then the patent examiner will submit his brief. The patent examiner’s brief has to be approved by his supervisor and it is not uncommon for a patent agent to receive a notice of allowance in a case because a patent examiner’s supervisor would not approve the examiner’s brief. The patent agent may request an oral hearing for the appeal. Bear in mind that the appeal procedure typically involves the payment of various fees.

Divisional application

As mentioned above, an alternative to filing an appeal in many jurisdictions is the filing of some form of “divisional application.” The term divisional application is used internationally to cover a variety of situations. In many countries, a divisional application is any application filed subsequent to the priority application. The definition of divisional application varies from country to country. In the US the term divisional application is typically limited to describing an application whose claims have been withdrawn from a patent application because the examiner did not find “unity of invention” in the pending application (e.g. the claims recited more than one invention). In the situation where an application has received a final office action and the time for response has run out, the patent agent will typically file a “continuing” application of some sort.

The US offers several types of continuing applications. The most common is known as an “RCE” or “Request for Continued Examination.” An RCE will retain the same serial number as its parent application – basically, the RCE is a mechanism that allows the review of the patent application to continue past the last final office action. Another form of application is the “continuation” application. This type of application will receive a different serial number from the parent application and is typically used when the applicant wants to pursue the patentability of a completely different set of claims from those in a parent application. Many practitioners will file one or more RCEs in an application before they file an appeal. The advantage of filing at least one RCE prior to an appeal is that by the time the RCE itself is under final rejection, the patent agent and the patent examiner will sometimes have reached a point where the discussion is exhausted and an appeal is appropriate. This point may be reached either earlier or later depending on the prior art, the pending claims and the parties involved.

4. Opposition proceeding:

Many countries’ patent laws provide for public opposition to the issuance of a patent. Some regional patent offices, such as the EPO, also allow for opposition proceedings. Depending on a country’s laws, the opposition may be conducted before the examiner reviews the patent application (pre-grant opposition) or after the examiner approves the application (post-grant opposition), or both. Oppositions are quite common in some jurisdictions. The patent agent should be aware that some companies routinely use oppositions as a mechanism for delaying issuance of their competitors’ patents and/or for reducing the scope of the claims issued to their competitors. Some public interest groups routinely oppose the issuance of patents in particular technical fields. Opposition papers are typically prepared by patent agents and for many patent agents, maintaining an opposition practice is simply a normal part of their regular work. Consequently, the patent agent should counsel his client that the mere receipt of an intention to grant a patent sent from a patent office does not necessarily mean that the client will receive his patent without further delay. 5. Issuance of patent: Once the patent examiner issues a “Notice of Allowance” or similar paperwork, the patent agent will need to complete various formalities related to issuance of the patent application as a patent. The patent agent may wish to ask his client if any form of continuation application is desirable. A continuation application will retain the filing date of its parent. For strategic reasons, it is often desirable to have a pending application where the patent agent can add new claims specifically tailored to a particular infringer. Alternatively, a continuation application will allow the inventor to pursue patentability for claims rejected during the first application. In many patent offices, applications may issue as patents many months after the patent agent has paid all the necessary government fees. (Patent issuance may be even longer if the jurisdiction provides an opposition process.) Unfortunately, there is not usually a way to speed up the printing and issuance of a given patent. Once the patent issues, the patent agent will not typically need to take any action with it beyond the payment of any periodic maintenance/annuity fees that may be required. The patent agent may wish to docket the dates for payment of annuity/maintenance fees as a service to his client.


[1] WIPO (2022), WIPO Patent Drafting Manual, 2nd edition. Geneva: WIPO.

[2] World Intellectual Property Organization (WIPO), available at:

Author is Mrs. Aehahini N, Assistant professor, Chennai Dr. Ambedkar Government Law College, Pudupakkam. She is a Gold medalist in family law and administrative law. She holds a Master degree in law from Tamilnadu Dr Ambedkar Law University and bachelor degree degree in law from Dr. Ambedkar Government Law college, Puducherry.

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