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Understanding the basics of patenting

Some practical advice on how to protect research that you are seeking to commercialize.

For many academic researchers and would-be entrepreneurs, the world of intellectual property and patents can seem intimidating, opaque and difficult to navigate, especially for first-timers. A familiarity with the fundamentals of patents is important to work effectively with the professionals involved so that you can reach your shared goal of an issued patent. In this article, we provide an overview of the patenting process, focusing particularly on concepts that are key to understanding patent fundamentals and the process by which they are approved. After reading this primer on patenting, you will have a basic understanding of all the important steps and also pitfalls that you should consider when protecting your research for commercialization.

Patent basics

Patents are a legal mechanism by which a governmental entity gives inventors the right to exclude others from using their invention or commercially exploiting it. In the United States, there are three types: plant patents, which protect new plant varieties; design patents, which protect a product’s ornamental or aesthetic aspects; and utility patents, which protect new compositions, methods, machines and manufactures (generally referred to as patentable subject matter). Utility patents are what most people think of when they hear the word “patent,” and they are the focus of this article.

The process of patenting an invention can be divided into four phases: deciding whether to patent, drafting and filing a patent, prosecuting your patent, and maintaining and enjoying the fruits of your patent (Fig. 1). We discuss these phases in detail below. Readers may refer to the glossary in Box 1 for further explanation of technical terms that are italicized when they first appear in the text.

Fig. 1

Key phases of the patenting process.

Phase 1: deciding whether to patent your work

Deciding to pursue a patent starts not with your discovery or idea, but with the eureka moment: when you realize that your idea or discovery solves a problem or addresses a need that people or companies care about. In other words, your invention has commercial potential. However, because patenting an invention is expensive and time consuming, and must be done in individual jurisdictions, the commercial potential of your invention should be evaluated before pursuing a patent. Patenting in any country makes sense only if it will generate far more revenue than it costs to obtain a patent. At universities and other non-profits, this evaluation is done by the technology transfer office (TTO).

Patents generate revenues by enabling new or improved products or by lowering the cost of existing ones. The cost of obtaining a patent includes the cost of drafting an application (generally between $3,000 and $15,000 in the United States), the cost of filing the application (approximately $3,000 for the United States, $7,000 for the European Union, $5,000 for China and $9,000 for Japan) and the cost of patent prosecution and issuance (typically at least $5,000 in each patent office). After issuance, there is the cost of maintaining and defending the patent in each country, until it expires 20 years after filing. Maintenance alone ranges from about $4,000 to $15,000 during the term of the patent in each country where there is a valid patent.

In addition to economic considerations, a vital criterion is whether the patent has a realistic chance of being granted. The US Patent & Trademark Office (USPTO) uses defined criteria to evaluate applications (see Table 1): is your invention patentable subject matter; does it have utility; is it completely novel; is the invention non-obvious (not a simple combination of known elements, for instance); is it clear what your invention is and that it works as described, and are you in possession of your invention (written description requirement); and can someone of ordinary skill in the appropriate field practice your invention without undue experimentation (in other words, is it enabled by the application)?

Table 1 Action, reaction

A particularly important question for determining novelty is whether you have publicly disclosed your invention in any way (a conference abstract, poster or presentation; a published paper; a dissertation). Public disclosure of the invention, whether by the inventor or someone else before the application’s filing date, means the invention is no longer novel and therefore cannot be patented. There is a one-year grace period in the United States, when the disclosure is made by an inventor; however, this exception may not exist in many foreign countries. It is our experience that for academic and non-profit institutions the most problematic criterion is non-obviousness. How all of these criteria are used to evaluate a patent application will be explained below.

A final question is, who owns the invention? While in the United States, as a starting point, the inventors own their inventions, this may not be the case in all countries. In the United States, employers, non-profit research institutions and companies alike typically require that employees assign to the employer their ownership rights for inventions made during employment, as well as their rights in any patents filed on those inventions.

Phase 2: drafting and filing a patent application

Drafting a patent application generally starts with the help of an in-house or external patent agent or patent attorney. Both are legally qualified to represent inventors at the USPTO, which requires having a technical degree (BS, MS or PhD) or equivalent coursework and passing the USPTO Registration Exam (otherwise known as the Patent Bar Exam). Because patent attorneys are also licensed to practice law, they can represent clients in court and give them advice on business-related legal matters. Although both can equally well represent the inventor’s interests, for the sake of brevity we use the term “attorney” rather than “patent attorney or patent agent” when referring to the applicant’s legal representative before the USPTO. Due to the complexity of the process, it is important to select an attorney with the right skill set. In the case of academics, it is usually the TTOs that pick the counsel using the general criteria of subject matter expertise, track record of obtaining meaningful claims, ability to work with inventors, and the attorney or firm’s billing rates.

Because a patent is a document describing an invention and telling people how to make and use it, inventors should provide the attorney all relevant data and information, including negative results (what doesn’t work can sometimes be just as useful as what does, especially in proving that an invention is non-obvious). Manuscripts and grant applications are particularly useful starting places for a patent filing. Inventors who made their invention using US federal government funding must also let the attorney know the federal grant number(s) associated with the invention; this is a condition of grants provided by the government and helps it track inventions made with federal funding.

Looking at online databases (, you will see that patents have multiple sections, the most important of which are the claims and the specification. It is the claims that formally describe and circumscribe the inventions that the patent will cover, and which the courts will use to determine whether the patent is being infringed upon. And it is the written description or specification, and any accompanying drawings, that tell people how to make and use the invention (in patent-speak, how to practice it). The specification also provides evidence, such as data showing that a compound has a therapeutic effect in vivo, that shows that an invention actually works, and supports the invention’s patentability.

A first step in this phase is establishing, among the inventor(s), the patent attorney and the intellectual property professional managing the process, an understanding what the invention is and what should be protected. Patent attorneys generally recommend this be done through an iterative process of drafting claims, during which the inventor(s), patent attorney and intellectual property professional come to agreement on the claims that will be filed. Their rationale is that, until the invention is defined by the claims, they don’t know what supporting information needs to be in the specification.

The claims can be divided into independent claims and dependent claims. The latter narrow the former by adding further limitations, such as by adding another element to a device, limiting the chemical moieties that can be substituted at a particular position on a compound, or inserting another step into a process. For example, if the independent claim is a seat comprising three legs (meaning it must have three legs, but additionally can have other elements), a dependent claim could be a seat having three legs and a back. Dependent claims can have additional dependent claims.

A difficulty in drafting claims is identifying the minimal set of elements that make the invention novel and non-obvious. This is critical because the fewer the elements defining an invention, the easier it is to prove infringement and the harder it is for competitors to invent around. Inventor input is essential to identifying this minimal set of elements. It is good practice to limit the scope of claims to inventions for which there is solid support or data so the claims have a reasonable chance of being allowed. Overly broad claims can cause problems both during prosecution and for future patents claiming improvements to the invention.

The claims are ultimately the core of any application, and most patents are written with several broad independent claims, each of which has multiple levels of focused dependent claims, including some targeted to cover specific applications or products. Preferably, they are written with an eye toward differentiating the invention from any prior art that may have been found during the patentability analysis. Attorneys often also claim inventions in multiple ways. For example, an application may include claims for a novel compound and claims for methods (method claims) of using it to treat a specific disease. They often also include claims that may seem repetitive, but actually describe the invention in slightly different ways, providing alternative paths to issuance.

Optimally, the claims provide multiple fallback positions, so that, even if broader claims are rejected, there are other narrower but still economically and/or strategically viable claims that can be made that may be allowable. A useful analogy are the multiple lines of defense encircling a castle: palisade, moat, outer battlement, inner wall, keep. Just as each line of defense of a castle encloses a smaller and smaller area, each level of the claims describes a narrower and narrower version of the invention. In patenting, as in defending a castle, whenever one line of defense falls (a broad claim is rejected), the defenders (the applicants) fall back to the next line of defense (a narrower dependent claim). And if the final line of defense is overrun and the narrowest claim is rejected, then the battle for the castle, and the patent, is lost.

Once the claims have been drafted, the attorney and inventors will draw up a specification supporting the claims. Applications must enable each invention claimed by teaching a person of ordinary skill how to make and use it without undue experimentation (too much tinkering). If the inventors have made and/or used (reduced to practice) the invention, the specification should describe in detail what they did and include any empirical evidence showing that the invention works for its intended purpose. Such a description allows the invention and its practice to be replicated by others. Absent actual reduction to practice, the inventors should describe, to the best of their knowledge, how the invention will be reduced to practice in the future (this is called constructive reduction to practice).

Although in many fields whether an invention will work is clear from its design (electronic and mechanical devices, for instance), the same is not true in fields such as biology and chemistry. These fields are so unpredictable that experimental data demonstrating that an invention works is required; constructive reduction to practice is thus insufficient to enable such inventions. In addition, experimental results beyond those needed for publication are often required to ensure that an application will both enable an invention and convince the patent examiner that it works.

To avoid narrow patent claims, a good specification will not stop with a detailed description of what was actually done. It will provide multiple options for each of the essential elements defining the invention, such as multiple ranges for their size, number, concentration, timing, dosing, composition and shape. The more options provided in the spec, the greater the flexibility in defining, and redefining, the invention in the claims during the prosecution.

Once the patent application has been drafted, a decision has to be made on the type of patent application to file. The first patent application(s) can be any of three types (Fig. 1): a provisional patent application, which is a placeholder patent application with lesser legal requirements than a non-provisional application, automatically expiring one year after its filing date; a non-provisional (regular or full) patent application with the potential to become an issued patent; or a Patent Cooperation Treaty (PCT) patent application, also known as an international application, a regular or full, placeholder application often used by those seeking international patent protection for an invention. The option of going straight for a non-provisional application is chosen when the applicants are confident that they have a fully defined invention and would like to speed up the allowance of the patent.

Another important step at the time of filing is determining the inventors who should be listed in the application. Inventorship is determined, usually with help from a patent attorney, on the basis of who made an inventive contribution to at least one claim. It should not be confused with authorship on a paper covering the same subject matter, as some authors may have made only non-inventive contributions.

The date on which the first patent application on your invention is filed is the priority date for the invention and any application claiming it. The priority date is important because it determines what is prior art. Prior art includes any information publicly available before the priority date, including patent applications filed before it. It is important to know that priority is accorded (the prior art date applies) only to those inventions fully supported by the application. That is why the description in a provisional should be as complete as possible. A half-baked provisional may get you an early filing date, but when a non-provisional based on that provisional is eventually examined, a lack of adequate support for any invention described in the provisional will mean that the priority date for that invention will not be the early filing date, but the filing date of the non-provisional.

Except in certain instances, filing a non-provisional application or a PCT application triggers publication of the application. The filing of a non-provisional or a PCT also triggers a prior art search. In the case of a PCT, the search will be performed and an International Search Report sent to the applicant within 16–18 months after the PCT’s earliest priority date. The International Search Report lists any prior art found and provides a preliminary opinion as to whether the inventions claimed are patentable. In the case of national-stage applications, a search will not be done until examination of the application begins (more on this below). Filing a non-provisional application also triggers publication of the patent application 18 months after its earliest priority date.

Provisional patent applications expire after one year but can be followed by a non-provisional or a PCT application claiming priority to the provisional at any time before expiration of the provisional (this is sometimes referred to colloquially as “converting” a provisional). Sometimes multiple provisionals filed within a one-year period are consolidated into a single non-provisional application. This is typically done when new data are generated during the year that significantly broaden or strengthen the original application. PCT applications can enter the national stage at any time before their expiration by filing the PCT as a national-stage application in a signatory country (there are 152 as of publication). National-stage applications can also be filed in regional patent authorities, such as the European Patent Office, which examines applications on behalf of multiple European Union countries. At most American universities (and subject to their respective budgets), the most promising inventions are typically filed first as a provisional, which is then followed by a US non-provisional and/or PCT at the end of the provisional’s one-year life. The PCT, in turn, is followed by national-stage filings before the PCT expires. Since the USPTO does not publish provisional applications, some applicants will occasionally abandon a pending provisional and file a new provisional application covering the same invention. This is typically done when not enough data are available to substantiate the claims made in the first provisional. This will result in the loss of the priority date from the first provisional and is a tactic to be adopted only when you are confident that you are still going to be the first to file, that no one else in the field is attempting to invent the same thing you are and that there has been no public disclosure about the invention by you or anyone else.

If a provisional application is followed by a non-provisional application, the priority date for the non-provisional is the provisional’s priority date only for the inventions that are fully supported by the provisional. However, if new matter is added to the non-provisional application, the priority date for the new matter, and for any claimed invention it supports, is the filing date of the non-provisional filing. If you make a new discovery related to the one you filed a provisional application for, after the date on which you filed the provisional, bring this to the attention of the attorneys before disclosing the idea in the public domain.

Once your application is filed as a national-stage patent application, it enters the examination queue, the length of which varies by patent jurisdiction (the national or regional patent office where the application is filed) and subject matter. Patent offices organize their examiners into groups according to their technical backgrounds, and each group examines applications whose subject matter falls within their area of expertise. The backlog of applications being processed by each group can vary greatly.

Phase 3: prosecuting a patent application

Once your non-provisional or national-stage patent application reaches the front of the queue in the relevant jurisdiction, the prosecution of the patent finally begins. Patent prosecution involves a back and forth between a patent examiner and applicant (Fig. 1). Patent examination entails reviewing the application for compliance with administrative requirements (for instance, are the drawings clear?) and evaluating the patentability of any inventions claimed, both according to the patent law of the relevant jurisdiction.

Because patent laws differ among jurisdictions, inventions are sometimes patentable in one and not another (the European Union, for example, does not allow methods of medical treatment to be patented while the United States does). Patent law differences also mean that the patent claims issued by separate jurisdictions may differ in what they cover and that a patent granted by one jurisdiction may be denied by another. Furthermore, interpretation of patent law within jurisdictions is always evolving. For example, recent court cases in the United States have rendered unpatentable diagnostic methods using naturally occurring relationships between levels of biomarkers and a particular disease state, as well as therapeutic biologics whose sequence of amino acids or nucleotides occurs naturally in any form. This was not the case in the past.

When a problem with the application and/or its claims has been identified (an objection or rejection), the examiner will issue an office action detailing the objection/rejection and any recommended actions to address it. Table 1 summarizes the most common objections or rejections in office actions and applicant filings in response to them. It is rare for no objections to be raised, but when this occurs inventors receive a first office action allowance. One common first office action in the United States is a restriction requirement, asking the applicant to choose among multiple inventions identified by the examiner and their associated claims. Only one invention will be examined per application fee.

The examiner’s evaluation of patentability begins with a prior art search. The search results and the application itself will determine, on a claim-by-claim basis, whether a claim should be rejected. If the examiner determines that some or all claims should be rejected, the examiner will issue an office action indicating which claims are rejected and which are allowed or allowable (the latter are claims where the reason for rejection is an easily fixed technical issue, such as incorrect claim grammar, improper references to other claims, or being dependent on a rejected claim), and why. The most common reasons for rejecting claims in the United States are listed in the left column of Table 2.

Table 2 Give and take

After an office action rejection is issued, the applicant has a prescribed length of time to file an office action response answering or countering the objections raised in the office action. The right column of Table 2 summarizes the most common applicant responses to office action rejections. If, after receiving the applicant’s response, the examiner determines that the rejection or objection has been overcome by the applicant’s arguments or claim amendments, the next office action will be a notice of allowance, and as long as the issue fee is paid by the payment deadline a patent will issue with the claims allowed. Otherwise, the examiner will issue another office action with objections or rejections, and the applicant will have a second opportunity to respond with arguments or amendments.

Inventors play an important part in drafting responses to office action rejections. For example, inventors can provide a deeper understanding of how their invention differs from the prior art found by the examiner. They can also undermine the relevance of prior art by pointing out details an attorney or an examiner might miss. They can also produce new data supporting the claims, such as in vivo data proving a treatment works, and they can provide guidance during the process of amending claims to prevent them from being narrowed to the point of business irrelevance.

The USPTO typically provides only two office actions for each application fee paid: an initial non-final office action and a subsequent final office action. The applicant can respond to both, but if their response to a final office action fails to overcome the rejection, the prosecution process ends and the application will go abandoned unless the applicant either ‘buys’ more office actions by filing a Request for Continued Examination (RCE) and (naturally) paying another fee (equal to the initial application fee) or files a notice of appeal. During the appeal process, others at the patent office, including the examiner’s supervisor, evaluate whether an examiner’s rejection is consistent with patent law. Sometimes the examiner’s rejection is legitimate and the applicant is unable to come up any new arguments to overcome it. Sometimes claims cannot be further narrowed without losing all commercial value. In both cases, the best course of action is usually to give up and abandon the patent application.

Regardless of whether a patent application is allowed, the applicant has the option, up to the date on which the application being prosecuted issues or until the final deadline for response to an office action, to file a continuation or divisional application. Both are identical to the original non-provisional application, except with different claims. A divisional’s claims are those previously withdrawn from the application in response to a restriction requirement, while a continuation’s claims are simply different than the originally filed claims (a continuation-in-part (CIP) application is an application containing new material added to the original specification). The priority date for both divisionals and continuations is that of the parent application (the first non-provisional application filed), but the priority date for the new material added in a CIP may be the filing date of the CIP.

Something those filing applications should be aware of is that everyone involved in the process of filing an application has a duty to disclose all relevant prior art material to (that is, which might affect) the patentability of one or more claims pending in the application. As an inventor, you should bring to the attention of the attorneys all relevant references, including your own publications and those of your peers, even if you think they are only partially related to your invention. Failing to do so may result in your patent claims being invalidated if they are ever challenged in court.

However long and difficult the patent prosecution might be, remember that the ultimate goal is securing an issued patent with claims that cover valuable products or provide a strategic business advantage; anything less is worth neither the time nor the money.

Phase 4: maintaining your patent rights

Congratulations! Your patent has been granted. Now that you have paid the issue fee, the patent will be given a formal serial number, be published with the allowed claims and become legally enforceable. However, for the owner to realize its full value, the patent has to be properly maintained and actively protected during its entire term. (Utility patents expire 20 years after their earliest non-provisional or PCT filing date, with adjustments made in a few jurisdictions, including the United States, for excessive delays caused by the examiner.) This includes paying periodic maintenance fees on time to keep the issued patent valid. In the United States, these are due 4, 7 and 11 years after issue, while in most other countries they are due annually (and are referred to as annuities). Many patent owners, including universities, evaluate whether an issued patent is still worth maintaining before paying a maintenance fee. They may choose not to pay the fee and allow the patent to go abandoned if it has been rendered obsolete by subsequent innovations or turned out to be less useful than anticipated, or if efforts to commercialize it have failed.

There is more to maintaining your patent rights than simply paying annuities. Issued patents can be challenged in post-grant patent challenges at a patent office or by being infringed. Although the details of defending against these challenges is beyond the scope of this article, any attacks on your patent challenge the validity of its claims. The best defense is to ensure that your claims and specification are well drafted to begin with.


The importance of patents in supporting the goal of commercializing science funded with public monies will continue to increase, and many universities expect scientific inventors to actively participate in patenting. However, like many other forms of legal protection, patent laws in the United States and other territories in the world continue to evolve due to new interpretations of the underlying laws.

It is important to bear in mind some important changes to US patent law in the past ten years that have reduced the scope of patent protection on inventions, such as biomarker diagnostics and algorithms1,2. Because the successful protection of intellectual property is also widely acknowledged as a crucial part of the innovation ecosystem, especially when it comes to areas such as start-up company creation and funding, it is important for you as an inventor to participate in all four phases of the patenting of your next invention. It is our hope this article will provide you with the knowledge to help you achieve this important objective.


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The authors thank R. Kadle, partner at Hodgson Russ LLP, for her comments on the manuscript.

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Correspondence to Sadhana Chitale.

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Chitale, S., Lawler, C. & Macfarlane, S. Understanding the basics of patenting. Nat Biotechnol 38, 263–270 (2020).

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