Patent Invalidation: Validity & Invalidity Search Yourself (Examples)

According to a report by WIPO, at the end of 2021, the number of active patents stood around 16.5 million, and this number was up by 4.2% in 2021 alone.

If you do not know about a patent, then a patent is a legal document that grants the patent holder exclusive rights to make, use, and sell an invention for a certain period of time. This exclusive right is conferred on him in exchange for his investment in the research and disclosure of the invention to the public for knowledge.

However, there are situations in which the validity of a patent may be challenged or “invalidated,” which means that it is no longer considered to be valid.

So, “patent invalidation” is the act of proving that a patent is no longer valid and should not have been granted in the first place. This can be done for a number of reasons, including if the patent was obtained improperly or if the invention is found to be not new, non-obvious or inventive.

Invalidating a patent can be a complex process that may require the assistance of a patent attorney and other patent professionals.

We will see every aspect of patent invalidation in detail in this article. So, hang on.

What is a Valid Patent?

A valid patent can enforce exclusive rights that come with it. An invalid patent is of no use.

A valid patent is enforceable in a jurisdiction i.e. a patent that has not been abandoned, withdrawn, revoked and declared invalid by a competent authority, disclaimed, canceled, or expired. So, a valid patent owner enjoys exclusive rights and stops others from making, selling, using, and importing his patented invention.

A valid patent has to be novel, inventive, and industrially useful.

If you take away the validity of the patent, its owner will no longer enjoy the monopoly rights. Therefore, for opponents’ and competitors’ best chance is to challenge the validity of the patent.

You can check whether a patent is valid or not on respective patent office websites. For example, the USPTO website for US patents, IPINDIA for Indian Patents, etc.

Patent Invalidation

It’s time we dive deep into the topic.

As we have seen, the patent right is a negative right, it stops people from using the patented technology for its lifespan of roughly 20 years. The lifespan of a patent may vary from country to country.

There are many claims in a patent. When we say there is an invention in a patent, we simply refer to the claims of the patent. Claims describe the invention and define the scope of the invention. Thus, if you invalidate one or more claims, you invalidate the invention disclosed in those claims.

It means, to invalidate a patent means to invalidate those claims. Infringement also happens claim-wise. In an infringement, you may not infringe on the whole patent, i.e., you may not infringe on all claims but some of the claims.

While trying to invalidate the patent, it may happen that you are able to invalidate some of the claims but not all. So if some claims are invalidated, the patent will still exist for the remaining claims.

Your primary focus should be those claims that you are infringing on.

You should know that all the granted patents are not of good quality. Many of them are granted in error or by overlooking some of the shortcomings of patent applications.

We can minimize the error in granting patents but can’t eliminate it completely because the process involves humans and to some extent, subjectivity is also involved.

This may work well for you if you are defending against an infringement claim by the patent holder. Basically, you try to find what was overlooked in the examination process, which you can use to your advantage now to challenge the validity of the patent or its claims.

In this context, if you happen to use a patented technology, you will be asked to stop using it, pay damages, or obtain a license from the patent holder.

If you do not stop using the patented technology, the patent holder may serve you with a legal notice and take you to court in a patent infringement case.

Here are a few options that you may have in such a situation:

1. Cease and Desist

If you are able to prove that you are not infringing on the patent, you may be able to have the suit dismissed by presenting evidence of no infringement to the court.

2. License:

You may be able to obtain a license from the patent owner, allowing you to continue using the patented technology in exchange for the payment of royalties.

3. Invalidate the Patent:

Generally, when you launch your product or process, you tend to conduct a freedom-to-operate (FTO) search. This gives you information on any existing patented technology that your product or process is using.

At the end of the FTO search, if you find your product or process infringing on an existing patent, you evaluate all your options in advance, including the validity of the infringing patent.

Therefore, in light of the FTO search, if you believe that the patent is not valid, you may be able to invalidate it through the provisions provided by the law of the land.

4. Settlement: 

If you are found to be using patented technology and you are not able to invalidate the patent, then you look for a settlement.

You may be able to reach a settlement with the patent owner, in which you may have to pay damages or obtain a license to use the patented technology, or you can acquire and merge the entity of the patent owner.

Note: It is important to seek the assistance of a patent attorney or other patent professionals in order to fully understand your options and make informed decisions in this situation. 

What are the ways to invalidate a patent?

As a business owner, inventor, or patent holder, you should be aware of the possible ways in which a patent can be invalidated.

1. Invalidation by anticipation:

A patent can be invalidated if it is found to be “anticipated,” which means that the invention described in the patent was already known or used by others before the patent was filed.

A claim of a patent is considered anticipated if all the features of that claim are disclosed in one prior document. We can do so for each claim.

To understand the Indian Point of view on anticipation, we refer to Section 29-34 of the Indian Patent Act. To understand US point of view, we refer to AIA 35 U.S.C. 102(a) and (b).

In order to be granted, one of the requirements is that a patent must be novel, or new, and not have been previously disclosed to the public.

2. Invalidation by obviousness

A patent can be invalidated if it is found to be “obvious.” But the question is: to whom should it be obvious?

Different countries have different criteria for judging obviousness. For example, in India, there is a hypothetical person called referred to as “person skilled in the art; in US, there is a hypothetical person referred to as person having ordinary skill in the art” (POSITA) for judging whether the invention claimed is obvious to him.

In order to be granted, a patent must also be inventive in addition to being novel. If it is found that the invention was obvious or not inventive according to the law of the land, the patent may be considered invalid.

Note: There is a difference between inventive step and obviousness. You can check out this article to learn more about this difference.

3. Invalidation by indefinite claims

A patent can also be invalidated if it is found to be “indefinite.” This means that the claims of the patent are not clear or specific enough to allow someone skilled in the field to understand exactly what is being claimed.

But why is it necessary that a person skilled can understand the invention by reading the patent specification and claims?

That is so because the basic principle of granting exclusive patent rights is that the patent owner or inventor has to disclose their invention to the world for knowledge so that the invention can be used for research and development purposes for now and can be used commercially by anyone once the patent expires. The disclosed information in the specification is only useful when it can be understood at least by the people from the field of patented technology.

Another reason that the claims should be specific enough is that if the boundary of the claims is not clear to you or if you can’t understand what is being covered in the claims of a patent then how do you know what is being protected by the claims and ensure that claims do not cover the invention for what they are even intended?

Note: Section 10(4) of the Indian Patent Act, 1970 talks about how the claims and specification of a patent application should be. Similarly, in US, 35 U.S.C. § 112 talks about the format of the specification including claims of a patent application.

Another matter that is to be talked about here is the not-patentable subject matter.

According to Article 27 of the TRIPS agreement, every country has a list of inventions that can not be patented. For example, India has Section 3 of the Indian Patent Act, 1970 (as amended i.e. latest after amendments) which prescribes what you cannot patent in India.

If the invention falling under non-patentable subject matter is granted patent due to subjectivity and interpretation of the law, then the patent can be invalidated later.

4. Invalidation by improper means

There are many formal/ technical requirements prescribed by the law of the land to get a patent from a patent office. The applicant may not always fulfill those requirements and may try to obtain the patent improperly. But when the truth comes out, such a patent may get revoked.

For example, if a company is applying for a patent for an invention invented by employees, it should have a proper agreement, such as proof of right from those employees/ inventors that enables the company to apply for a patent and own it partially or fully.

If there is a chance of fraud in obtaining proof of right, and it is proven so, then the patent may be revoked as it was obtained improperly.

Similarly, if the patent law of a country (Section 8 of the Indian Patent in India, for example) mandates disclosure of all the foreign filing details and prosecution history of the corresponding patent applications and the applicant chooses to hide some of the important foreign filing details, then the patent may be revoked once it is brought to the notice of the designated authority.

But why are foreign filing details are needed, anyway?

That is because if a patent application is refused in one country on some ground, then on the same ground, it may be refused in another country. Therefore, the applicant of a patent application may choose to hide such details. A patent obtained by hiding details in this manner will be an improperly obtained patent and is, therefore, eligible for revocation.

There are many grounds not covered in this article as each country has its own grounds for invalidation and revocation. But these should be enough to give you an idea about how a patent can be invalidated.

Note: Checkout Section 64: Revocation of patents of the Indian Patent Act, 1970 laying grounds for revocation of patents, for example. Other relevant Sections to revocation of patents in India are Section 65: Revocation of patent or amendment of complete specification on directions from Government in cases relating to atomic energy, Section 66: Revocation of patent in public interest, Section 85: Revocation of patents by the Controller for non-working.

Where You Can Challenge the Validity of a Patent?

Every country has a different mechanism to address the post-grant patent revocation proceedings. Below, we are going to discuss provisions available in US and India to give you an idea about how it all works.

Provisions in the US to challenge a valid patent

In the US, in addition to courts, there are less expensive and quicker provisions to settle invalidity matters quickly: “post-grant review,” “inter partes review,” and “ex parte reexamination” to challenge the validity of a patent.

1. Provision of “post-grant review” is available up to nine months after the grant of the patent and is conducted by Patent Trial and Appeal Board (PTAB).

2. “Inter partes review,” was enacted as a part of the America Invents Act (AIA Act) on September 16, 2012. It replaced earlier existing “inter partes reexamination” proceedings.

In “inter partes review,” at any time (once the nine months after the grant are over or the post-grant review terminates) after the granting of the patent, a third party requests the patent office, the USPTO, to assess the validity of the claims of the patent.

The review is conducted by the PTAB. It was brought about to reduce litigation costs and deliver quicker results. The PTAB, the patent owner, and a third party are all involved in this.

During an inter partes review, the PTAB considers the “prior art” (previously existing knowledge or technology in the relevant field) and determines whether the claims of the patent are novel and non-obvious in light of that prior art.

If the PTAB determines that the claims are not patentable, they will be cancelled or claims of the patent will be invalidated. 

The burden of proof in this process lies with the third party requesting the review.

The decision can further be appealed in United States Court of Appeals for the Federal Circuit.

The main difference between post-grant-review (PGR) and inter-partes-review (IPR) is that PGR can be availed of for any ground related to patent invalidity under 35 U.S.C. § 282, but IPR can only be availed of for a ground related to patent invalidity under 35 U.S.C. §§ 102 and 103 and on the basis of patents or printed publications.

Note: The burden of proof in “post-grant opposition” and “inter-partes-review” lies with the petitioner who petitions for review. The important thing to note is that in both of these proceedings, the burden of proving non-patentability on the petitioner is lower than that of litigation.

3. “Ex parte reexamination” is another way in which the patent office reexamines the patent at the request of a third party or the patent owner himself.

However, once the reexamination starts, only the examiner and the patent owner are involved, for the most part, in checking the patentability of the patent in light of the request.

If a patent is invalidated, it is no longer considered enforceable, and the holder of the patent will no longer have the exclusive rights to make, use, and sell the invention.

This can have significant implications for the patent holder, as they will no longer be able to prevent others from making, using, or selling the invention.

Provisions in India to invalidate a patent

In India, a granted patent can be revoked:

(1) “on a petition of any person interested or a petition of the Central Government” by an Appellate Board (Intellectual Property Appellate Board (IPAB), which is no longer in existence after it has been abolished), or

(2) “on a counter-claim by the defendant when he is sued for infringement of the patent” by a High Court.

(3) There is also a provision for post-grant opposition, which can be availed of within 12 months of the publication grant of the patent in the journal. In post-grant opposition, the interested party can request and oppose the grant at the Indian Patent Office.

After IPAB was abolished in India, all matters pertaining to IPAB were transferred to the High Court.

As we have seen previously, Sections 64, 65, 66 & 85 of the Indian Patent Act, 1970, deal with “Revocation of Patents”

Examples of Patent Invalidity in the US

Here are real-life examples of patent invalidation in lawsuits, along with some additional information about intellectual property:


The patent involved in EON CORP. IP HOLDINGS LLC v. AT&T MOBILITY LLC case was US5663757A. The district court found that the claims were indefinite in scope and therefore, invalid.

Basically, patent claims were about software for interactive TV features. The software allowed various features such as “impulse purchase transactions with immediate payment”, “audience participation voting, ”audience participation in voting” and “sorting television programs by theme”, etc.  

Eon filed an infringement suit against multiple companies, including AT&T. The district court, in this case, granted a summary judgment that found all claims of the ‘757 patent invalid as they were indefinite in scope.

Eon appealed to the United States Court of Appeals for the Federal Circuit. However, in conclusion, the Federal Circuit affirmed the district court’s grant of summary judgment of invalidity. Thus, all claims of the ‘757 patent were declared invalid for indefiniteness.

This example shows how you can defend against an infringement suit by invalidating the patent itself. This also shows that although the claims were found patentable by the patent examiner at the USPTO, including the definitive scope of claims, later, the findings of the patent examiner were overturned by courts, and the patent was eventually declared invalid.


The case ULTRAMERCIAL, INC. v. HULU, LLC was decided by the United States Court of Appeals for the Federal Circuit on November 14, 2014.

The patent in the case was US 7,346,545 B2 which related to a method for distributing copyrighted content over the InternetIn this invention, users could access copyrighted material by watching advertisements, and the price would be paid by the advertiser company.

For this patent, Ultramercial sued Hulu, LLC (“Hulu”), YouTube, LLC (“YouTube”), and WildTangent.

In this case, WildTangent argued that the ’545 claims are directed at the “abstract idea” of offering free media in exchange for watching advertisements and that the mere implementation of that idea on a computer does not change that fact.

The Federal court concluded that ‘545 patent claims are directed to no more than a patent-ineligible abstract idea and also remarked that the district court was not wrong when it concluded the same about the claims of the patent.

So, this time, the patent was invalidated because it did not contain subject matter that was eligible for a patent as it claimed more of an abstract idea.

However, it is also important to note that the patent application was able to pass the examination phase through the patent examiner at the USPTO despite having patent-ineligible subject matter.

Because the examination of a patent application is subjective to some extent, it is reasonable to expect that decisions by different entities can change at various stages.

Therefore, it is possible to get the infringing patent invalidated with proper homework and save your money and business.


The case PERSONAL AUDIO, LLC v. ELECTRONIC FRONTIER FOUNDATION was decided by the United States Court of Appeals for the Federal Circuit on November 7, 2017.

The patent in question was US 8,112,504 B2 and was owned by Personal Audio LLC, which was related to a system for organizing and distributing media files.

Claims 31–35 of this podcasting patent were invalidated. The PTAB found that these claims should not have been granted in light of two prior art references, one relating to CNN news clips and one relating to CBC online radio broadcasting.

Personal Audio appealed that decision to the Federal Circuit, which upheld PTAB’s decisions. Further, Personal Audio went to the Supreme Court of US which denied the petition. Therefore, the PTAB’s decision became final.

In order to be eligible for a patent, an invention must meet the requirements of novelty, non-obviousness, and utility. But in this case, the patent was not novel, i.e., anticipated by CBC’s online radio broadcasting reference and alternatively was found to be obvious by CNN’s reference.

Examples of Patent Invalidation in India

1. Biswanath Prasad Radhey Shyam vs Hindustan Metal Industries

This case was decided by the Supreme Court of India on December 13, 1978.

Bisawnth Prasad Radhey Shyam, the petitioner, filed a petition against the respondent, Hindustan Metal Industries alleging that the respondent has infringed on their invention which is “a device and method for manufacturing utensils, introducing improvement, convenience, speed, safety, and better finish, in the old prevalent method which was fraught with risk to the workers, in as much as the utensils used to fly off from the headstock, during the  manufacturing process ”

The case went to a trial court and an appellate bench, and at last, the case went to the Hon’ble Supreme Court (SC) of India. In this case, the SC concluded that the “patented machine” was neither a manner of new manufacture or novel improvement nor did it involve any inventive step, having regard to what was publicly known or used at the date of the patent.

The grant of the patent in question was, therefore, invalid and was liable to be revoked on the grounds mentioned in Clauses (d) and (e) of Section 26(1) of the Act.”

Note: Here, the SC referred to Section 26(1) of the Indian Patent and Designs Act, 1911, and not the current Patent Act, 1970, because the matter started in September 1952 with a notice to the respondent.

This example highlights the importance of an invention to pass the patentability criteria and the defense option even after you are sued for the infringement.

2. Enercon (India) Limited V. Aloys Wobben Argestrasse

The patent, in this case, was IN201538, granted to Dr. Aloys Wobben for “A method for operating a wind turbine with an electrical generator and a wind turbine with an electrical generator.”

The patent relates to a wind power installation in which the phase angle of the power varies if the voltage is outside a particular range of values.

Enercon India Limited filed an application for revocation in front of IPAB. Enercon debated the subject matter was not inventive in view of cited documents. The IPAB found the invention claimed in the patent invalid and revoked the patent.

You can also check its status on INPASS which shows “revoked” (you can check it with the patent number 201538 or other details shown in the image below).

How to Perform Validity Search Yourself

Guide to perform validity Search yourself?

So far we got to know the concept of patent invalidation, it’s time we learn to perform the validity search as well.

Whether you are an entrepreneur, a patent attorney, a professional patent researcher, or simply curious about patents, this guide is perfect for you.

Just like every project, there is a step-by-step approach to conducting an invalidity search to get a patent revoked as per the law.

There are many ways you can get the patent revoked. For example, Sections 64, 65, 66, and 85 of the Indian Patent Act, 1970, list grounds on which a patent can be revoked in India.

Some grounds for revocation of a patent are common in different countries, be it US, India, or Europe. These grounds include proving that the patent was improperly obtained, was not novel, was obvious, etc. 

During an invalidity search, if you are able to unearth strong prior art proving that the patent obtained was actually not novel, not inventive, or was obvious, then you stand a real chance of getting the patent invalidated.

Our focus in this guide is on the search.

If a company is sued for infringement or finds a potentially risky patent of its competitor’s while conducting a freedom to operate search then it looks to invalidate or revoke that patent otherwise its business may be affected negatively.

Who initiates the validity search and why?

Let’s look at a few examples involving situations where a validity search is required. Situations may involve infringement dispute, freedom to operate, merger & acquisition, licensing, patenting similar technology, etc.

1.1 Example: validity search to settle infringement dispute

So, imagine a scenario where company X holds a patent for data transfer technology via Bluetooth and is a leader in the Bluetooth space.

Another company Y is a startup and comes up with a great Bluetooth speaker that uses the patented data transfer technology of company X.

Since X is a large company, it holds hundreds of patents. Company X also has a large team of patent professionals to manage its patent portfolio. These professionals regularly carry out infringement searches and prepare evidence of use (EoU) charts so that X’s large patent portfolio can be monetized one way or another.

Note: An infringement search for a patent is conducted to see if there is any product or process in the market that may infringe on the patent.

If such a potential product or process is found in the search, we map the features of a claim of the patent to the features of that product or process i.e. one-to-one mapping.

This way, we record evidence of the use (EoU) of the patent by the product or process in a chart or a report. We call it evidence of use chart or EoU charts.

Now that you know what an infringement search is and what the EoU charts are from the previous section, you can understand that in one such infringement search, the patent team of X finds the speaker of Y using the claimed features of their patent.

Subsequently, they prepare an EoU chart as a first step.

After they have a chart showing the evidence that the speaker of Y is using claimed features of a patent owned by X, they send a notice to X with their demands. Demands may include paying up the damages, ceasing and withdrawing the product, paying a royalty, settling in court, etc.

Here comes the fun part.

Company Y, however small, is a smart one. They had conducted a Freedom-to-Operate search before they launched their speaker using Bluetooth data transfer technology.

In the FTO search, they already found the patent of X that we are talking about and knew that their speaker is infringing on the said patent.

At that time itself, Y had considered all of their options, including whether the patent could be invalidated, should the need arise.

As expected, X sues Y for infringing on their patented technology.

In such a situation, Y will reach out to the patent professionals to search for strong prior arts that could prove that X should not have gotten that patent in the first place as it failed the patentability requirements.

If Y becomes successful in getting one or more strong prior arts, they can continue selling their speaker using Bluetooth data transfer technology unchallenged and save their business.

It is not that Y will conduct the invalidation search only after getting sued or will wait to get sued before attempting to invalidate the patent of X. In fact, Y can initiate invalidation proceedings with the Patent Office, the Appellate Board, or the Court as per the provisions of the land.

1.2 Example: validity search to assess the portfolio for merger & acquisition

If company A wants to have business relations with company B by acquiring or merging with it because company B happens to have a portfolio of patents that are of interest to company A.

However, company A, before investing in a relationship with B, would want to know the validity, strength, or value of the patents in B’s portfolio.

There is no point in buying or acquiring licenses to patents that can be invalidated and, hence, are weak in nature.

In such a case, company A reaches out to the team of patent professionals to see whether patents in company B’s portfolio are valid by conducting an invalidity search.

Even if the patents turn out to be valid, the patent team helps company A assess the value of company B’s portfolio based on various factors, including how strong and useful the patents are.

1.3 Example: validity search before decision making

If company C wants to file a patent application related to a particular technology, then it would conduct a patentability search.

Now suppose that, during a patentability search or by some other means, company C comes across a potential patent from company D in the same technology.

Moreover, company C finds that the patent held by D can pose a challenge, as C’s patent alone would not suffice to implement the technology in a product.

In fact, the condition is such that without permission to use the technology of D’s patent, C would not be able to do much with their patent.

In such a scenario, C opts for an invalidity search before considering licensing, acquisition, or merger to see whether it can challenge the validity of D’s patent.

Now that you have seen some examples illustrating where the need for a “validity search” may arise, Let’s

Let’s look at how you can conduct the same if you are approached by a company or an interested party.

So, what are the steps that you have to follow to carry out an invalidation search?

  • Step 1: Read, understand, and brainstorm the patent to be invalidated
  • Step 2: Finalise the scope of the search
  • Step 3: Hunt for the search material
  • Step 4: Carry out the search
  • Step 5: Analyze the retrieved results
  • Step 6: Prepare a report and communicate

Note: We have written a comprehensive guide covering the fundamentals of conducting a search for prior art including the steps needed for a validity search:

In this guide, you will learn everything you need about searching from beginner to pro level. The core concepts of the search remain the same be it validity search, novelty search, FTO search, landscape search, or any other kind of customized search, therefore, this guide serves as a great platform for you to start your career as a patent searcher.


In conclusion, patent invalidation/ invalidity can help save your business and give you an edge over your competitors. If you are a patent professional or a student learning about this topic, then you should be aware that learning and perfecting the art of searching and advising businesses on how to navigate through patent validity and infringement issues can boost your career.

If you are a researcher or individual inventor, knowing about patent invalidation and how to conduct a basic search can give you an additional edge in your research work or in your invention.

In this blog post, we discussed what is patent invalidation, what are your options if you are charged with infringement, what are the ways to invalidate a patent, various related provisions in USA and India, real-world examples to understand the topic, and how to perform validity search, etc.

We hope that this post has provided valuable insights and inspired you to dive deeper into the subject. Be sure to check out our other resources on our platform. We have a wealth of information on patents and many related subjects that can help you continue your learning journey. Thank you for reading.

Sonam Singh

My struggle, in the beginning, made me realize the need to create an ultimate resource that can provide answers to both very basic questions like what, why, when, who, how, where, and the most complex topics about intellectual property. Moreover, my passion for writing and my love for patents made it easier for me to create this super-helpful platform for students, professionals, and curious minds wanting to know about IP. Cheers to that.

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