If you’re new to the patent world, you’ve almost certainly heard the term “prior art” — but probably didn’t know exactly what it meant. It’s one of the most important and frequently used concepts when you’re building a patent portfolio, and that’s because it plays a significant role in determining the patentability of your inventions.
Defining prior art may seem simple enough, but there’s a lot of nuance and subtle complexity that can tank an important patent application or patent family if you’re not careful. And beware: You could even accidentally create prior art against your own inventions!
You could say that there is always prior art when you file a patent application — so let's discuss how you can develop a patent portfolio that strategically navigates prior art obstacles. We’ll also explain what it means to be patentable over prior art and share smart strategies you can employ to minimize the risk that your patent claims will get knocked out by unexpected prior art.
Prior art is one of the most common reasons the USPTO gives for rejecting claims in patent applications. It can be used to show that your invention is not “new” or “non-obvious” — two of the most important requirements that determine whether your invention is patentable. That’s why it’s important to understand what counts as relevant prior art, and how that can affect your patent application.
Technically speaking, what is considered prior art under U.S. law is defined by federal statute 35 U.S.C. 102, which was most recently amended by the America Invents Act (AIA) — changes to the definition of prior art took effect in March 2013.
|In simpler terms: Prior art is any evidence that your invention was already publicly known or available, in whole or in part, before the effective filing date of your patent application.|
Nevertheless, that’s still a fairly broad concept. To better pin down what prior art is (and isn’t), let’s take a deep dive into several specific examples.
Many people make the mistake of assuming that prior art is limited to either existing products or issued patents. In other words, they believe (wrongly) that they’re entitled to a patent for an invention simply because that invention hasn’t been patented or implemented in a product yet.
But the range of information that counts as prior art is much broader than issued patents and commercial products. Generally speaking, prior art arises when someone has either made an idea available to the public (commercially or otherwise), or filed a patent application that was eventually published or issued as a patent.
To list some common examples, prior art can include the following:
A product that was available for sale
Commercial use of the invention
Articles, publications, or journals
Presentation at a public event (a trade show, conference, etc.)
Public knowledge or use of the invention
A previously filed patent application
With the exception of previously filed applications, the above examples have something in common: They were publicly available or publicly disclosed before you filed your patent application. It doesn’t matter whether the information is broadly accessible on the internet — factors like target audience, language, number of copies made, and geographic location are irrelevant. To use an unlikely example, a high school textbook published only in Kazakhstan could still count as prior art.
Additionally, the information must have been publicly disclosed or publicly available before the effective filing date of your patent application. If your effective filing date is Sept. 1, 2017, then a magazine article published on Aug. 31, 2017, counts as prior art — as does an expired patent from 1950. However, provided you filed on Sept. 1, a demonstration of your product later in the month won’t qualify as prior art.
Previously filed applications are slightly different from the other examples though, because a previously filed patent application might not be publicly available or publicly disclosed at the time you file your patent application. Patent applications typically remain secret for months or even years before they become public (as a published application or an issued patent).
But a previously filed patent application can qualify as prior art even if it becomes public only after your application is filed. So for example, if your effective filing date is Sept. 1, 2017, another patent application that was filed on Aug. 31, 2017, counts as prior art — even if it’s not published for several years.
Information that becomes publicly disclosed or publicly available only after your application’s filing date generally doesn’t qualify as prior art. Similarly, patent applications filed after yours generally don’t qualify as prior art.
Here are four other notable exceptions to the examples provided above.
To qualify as prior art, a publication must disclose the invention with sufficient detail — specifically, an “enabling disclosure” is required. Put another way, if someone with ordinary skill in the relevant field of technology cannot figure out how to make and use the invention from the prior disclosure, then it can’t be used as prior art to reject your patent application.
Let’s say you figure out how to build Iron Man’s suit and want to patent it. The comic books and movies themselves would not qualify as prior art in your patent application, because although they explain what the suit does, they don’t provide enough information to enable the average skilled person to build the suit.
Under certain circumstances, abandoned patent applications may remain confidential, disqualifying them as prior art. For one, provisional patent applications that aren’t converted to non-provisional applications are never published.
By default, non-provisional applications are published 18 months from filing. However, an application will not be published if the applicant abandons it more than four weeks before it’s due to be published.
Alternatively, if the application was filed only in the United States, the applicant can request non-publication — in which case the application will not be published unless and until a patent is granted.
As trade secrets are confidential by nature, they cannot be used as evidence of prior art. So another company’s trade secret invention typically couldn’t be used as prior art against your patent application, even if the other company developed their trade secret before you independently developed the same invention.
Even though it’s not advisable, in reality technology companies often need to disclose their work to third parties before they file a patent application. Reasons to do this include gauging market interest, pursuing funding opportunities, and developing collaborations with other groups.
When information is shared with third parties under an obligation of confidentiality, the disclosure doesn’t count as prior art against your patent application. The best way to ensure that a disclosure will be considered confidential to have all parties sign a non-disclosure agreement.
First of all, many people assume that you’re required to do a prior art search before you file a patent application. But that assumption is wrong. You don’t have to do a search!
That said, doing a prior art search can often lead to a more valuable patent application. Broadly, if you know about the most relevant prior art before you file, you can develop a more strategic patent application at the outset. You’ll also be better positioned to determine whether it’s worth pursuing a patent application for your invention, saving you time and money in the long run.
By familiarizing yourself with the existing prior art, you enjoy the following benefits:
It’s common for patent attorneys to discourage inventors from doing a prior art search on their own. As the argument goes, it’s best to leave the legal footwork to the legal experts.
But if you’re an expert in your field of science and engineering, outsourcing your prior art search may not always be the best use of your limited budget. You’re probably already well-equipped to conduct an effective prior art search on your own.
Back in the good old days (pre-Internet, pre-Google), expert prior art searchers had access to more resources (specifically at the USPTO) than the ordinary person, and they used special techniques for effectively searching special patent databases.
But today, the internet provides 90 percent of the same value — for free.
And anecdotally, every time I’ve been to the USPTO, the search rooms have been virtually (or literally) empty, suggesting that people just don’t use them much anymore.
So you can do the prior art search effectively on your own because the best search tools are available for free online. The only exception is if you’re working in a technical field where you don’t have extensive experience; in that case, you should probably hire someone to do the search for you.
Still, keep in mind that while you can conduct the prior art search yourself, you’ll likely still need a patent attorney to help you develop a patent strategy and analyze patentability.
Simply put, a prior art search involves checking different databases to find out whether someone else has already described an idea similar to yours.
Here are five steps to follow to ensure your prior art search is comprehensive.
To conduct a thorough search, you’ll need to account for all possible keyword combinations that could exist in the prior art.
There are various reasons why other patents and applications may use unusual keywords:
We recommend the following patent search tools to kickstart your search:
Many practitioners find that the “classification” system used by the USPTO (that is, the classes and subclasses assigned to each patent) is not particularly useful for prior art searching. As such, we don’t recommend using it as the primary means to guide your search.
Instead, we recommend making a list of the top 10 patent documents for each keyword — and then looking at all the other patent documents that reference, or are referenced by, that patent document. This is sometimes called a “forward and backward” cross-reference search.
To do a “forward and backward” cross-reference search in Google Patents:
To do a similar search on the USPTO search interface:
You’ll also see a section for “Non-Patent Citations.” While these documents are not always easy to find online, you may be able request a copy from the patent office.
Prior art isn’t limited to existing patents or patent applications; it includes all ideas that are publicly available and publicly disclosed. As such, a complete prior art search should extend beyond patent searching.
The following list is not exhaustive, but your prior art search could include:
When filing your patent application, you want to cite the most relevant prior art to the USPTO. If the patent examiner has all the most relevant references at their disposal, you’ll end up with a stronger patent.
Additionally, this will ensure you satisfy your ethical duties of disclosure, candor and good faith to report prior art that could affect the patentability of a claim.
So make sure you save a list of all relevant results, as well as complete copies of the documents themselves. (We love a good spreadsheet!)
Your goal is not to examine all the prior art out there. Rather, it’s to examine enough prior art to gain a comprehensive understanding of where your invention stands in the industry. I often tell folks that we want to get a good “sampling” of the prior art, as opposed to an exhaustive study of it.
It’s impossible to know the entire universe of prior art that may be relevant before you file a patent application.
For one, thanks to the 18-month publication window, some patent applications that qualify as prior art may not become public until later on. It’s literally impossible to find these in a search before you file your patent application.
For another, there may be relevant prior art that doesn’t show up in a typical search (even after they’re public). Examples include documents that are not indexed on Google, academic theses, and foreign language documents.
So if your search isn’t turning up much prior art, you might be tempted to keep going — but use your experience and common sense to decide when to call it a day.
There’s always going to be prior art for any invention. In the words attributed to a famous federal judge, “Only God works from nothing. Man must work with old elements." Patentability doesn’t hinge on the existence of prior art. Instead, whether your invention is patentable depends on how different your invention is from the prior art.
There are two criteria for patentability over prior art:
First, the invention must be new (or “novel” in the words of the statute) — which generally means it can’t be identical to any single product or reference. Quite simply, this prevents you from patenting ideas that already exist in the public sphere or in previously filed patent applications.
At the next level, your invention needs to be inventive (or “non-obvious” in the words of the statute) — that is, more than a trivial variation of prior art. That means an invention typically can’t be patented if a person of ordinary skill in the relevant field of technology could derive the invention from the prior art by making obvious changes or substitutions.
So prior art can be used to invalidate the claims in a pending or issued patent by showing that the claimed invention is not “new” or “non-obvious.” For this reason, it’s important to understand how discovering prior art could affect your patents and applications.
If you discover relevant prior art before your patent has been issued, this is relatively easily resolved. You’re obliged by your duty of candor and good faith to disclose the prior art to the USPTO. You can do this by filing an information disclosure statement (IDS), which allows you to inform the USPTO of any background art during the patent prosecution process. And generally speaking, you’ll have the opportunity to amend the claims of your pending application to differentiate from any newly discovered prior art.
If you discover the prior art after the patent has already been issued, there’s no obligation to cite the prior art in your issued patent. But should your competitors discover the same prior art, they could potentially use it to knock out your patent’s claims via litigation — more on that soon.
In the rest of this section, we’ll help you to determine whether your claims might be vulnerable to invalidation in a litigation context, and whether pursuing remedial measures is the right next step.
A patent as a whole is not invalidated by prior art. It’s more accurate to say that claims are invalidated by prior art. So it’s unlikely that your entire patent will be invalidated — unless the prior art invalidates all of your patent’s key claims.
Generally speaking, a patent is divided into a specification, drawings, and claims. Patent claims are the most important part of the document because they define the exclusive right granted to the patent owner. The rest of the patent essentially offers context — facilitating an accurate understanding of what the claimed invention entails.
Just because one or some claims have been invalidated doesn’t mean that the entire patent is invalidated. Each claim in an application is considered to stand on its own, and is assessed separately from the others.
For this reason, the differences between independent and dependent claims could make a world of difference to a patent’s ability to withstand challenges:
Here we’re using the term “litigation” broadly to mean any type of adversarial legal process. For example, it can be a lawsuit in federal district court, a USPTO proceeding (such as the IPR process), etc.
The validity of an issued patent can be challenged based on prior art in a litigation context on either of the following grounds (which are similar to the criteria your USPTO examiner would’ve used to assess your initial application):
As mentioned earlier, the independent claims are the broadest claims in a patent, with each one typically having a chain of dependent claims of narrower scope. So if an independent claim is novel and inventive, then generally all the claims that are dependent on this claim are novel and inventive. As such, it’s ideal for your independent claim to stand.
However, even if prior art knocks out an independent claim, the dependent claims may still remain valid because they’re necessarily narrower.
How? A dependent claim could include additional elements that are 1) not in the prior art and 2) not obvious in view of the prior art. This dependent claim would not be invalidated by the prior art.
That’s why robust dependent claims are critical in a patent: They provide a “fallback” position in a litigation context. If the independent claims are found to be invalid because of newly discovered prior art, the dependent claims might still be valid, enforceable, and very valuable.
If a prior art reference discloses only what’s in a dependent claim (but not what’s in the independent claim), then the dependent claim typically can’t be knocked out by the prior art reference alone.
For instance, suppose an independent claim recites a widget comprising components A and B, and the dependent claim adds component C. Prior art that describes only component C wouldn’t make the claims unpatentable — unless the prior art reference also describes components A and B. Similarly, prior art that describes components A and B (but not C) wouldn’t make the dependent claim invalid.
But if the prior art discloses what’s in both the independent and dependent claims (A+B+C), then both claims would fall.
Whether you’ve discovered prior art against your own or a competitor’s patent, it’s best to speak to an experienced patent attorney for advice on how to handle your unique situation.
More often than not, the best thing to do is nothing at all. (How many times do you hear a lawyer say that?) But if the patent you’re looking at covers valuable technology that your company is using or might potentially use, you should definitely develop a strategy with your legal team.
It’s also possible to inadvertently create prior art against your own patent applications. This typically occurs as a result of carelessness — for example, when you don’t keep track of your dates of public disclosure, or don’t ask your employees to follow strong confidentiality policies. Use this five-step checklist to ensure that you’ve covered all your internal bases.
If you’re planning to sell, offer for sale, demo, or disclose your invention (whether publicly or non-publicly — so for example, through a public presentation or in a marketing strategy), file your patent application beforehand to avoid creating prior art.
In cases where you must disclose your invention before filing a patent application (for example, when you’re shopping your invention to venture capitalists), you may be able to maintain confidentiality by getting all third parties involved to sign a nondisclosure agreement.
If confidential information becomes public or ends up in the wrong hands, you may lose the right to file for patent protection or claim trade secret status. As a practical matter, when confidential information is improperly disclosed or used, it’s typically through people — specifically, your employees — which is why your human resources (HR) department plays a key role in maintaining the integrity of your intellectual property.
Have all job candidates sign an NDA before they’re allowed to interview. This puts candidates on notice that any company information shared with them during interview must be kept confidential, even if they aren’t offered the position.
In addition, every employee who might contribute to the company’s intellectual property should sign an employment agreement before they start work. The employment agreement should clearly define what IP is owned by the company; usually, this encompasses all IP developed by the employee over the course of their employment.
|Learn how to create effective hiring practices
on our blog.
Your company’s IP policy should be emphasized through a formal training course for all new employees. Subsequently, it should be communicated in written documents available to employees for reference, and further reinforced through at least one “refresher” course per year.
The exit interview is your best opportunity to check in with a departing employee, and ensure that they no longer possess or have access to any confidential information.
And depending on the employee’s role and ability to access information, you’ll also need to revoke their access to all locations where they could have stored information.
|Read a more in-depth take on enforcing confidentiality policies on our blog.|
Invention disclosure records (IDRs) — which often go by other names such as “invention memos” or “invention disclosure forms” — are internal documents where employees provide all the relevant details about their company-related inventions. Basically, they’re useful tools that help your company track the IP that its employees have created.
In particular, IDRs can help you maintain better factual disclosure (inventorship, dates, etc.) in order to meet important deadlines in the patent process.
|Don’t know how to write your own IDR?
Use our free template and never miss a key detail.
It’s possible for your own previously filed applications to be used against your current application as prior art.
Generally speaking, your company’s previously filed application can be counted as prior art if it’s published more than a year before your current application. So if you realize that the one-year deadline is approaching, you may need to file a patent application quickly.
The laws governing previously filed applications as prior art are quite technical and complex, and vary by country. Next, we’ll help you gain a more in-depth understanding of the issue under U.S. law.
Here, we’ll be deep diving into some pretty nerdy stuff about one particular U.S. statute. Accordingly, what we’re about to discuss is specific to U.S. law; the laws are different in other important jurisdictions (e.g., Europe, China, Japan).
Oh, and this bit will be super-technical — consider yourself forewarned!
Most patent attorneys are now very familiar with the changes in U.S. patent law that were created by the America Invents Act (AIA), which was passed in 2011 and took effect in 2012 and 2013. In fact, those of us who practiced under pre-AIA law might even have kicked the habit of referring to “old 102(e)” and other sections of the statute that were axed by the AIA.
Though most folks would be quite comfortable with post-AIA law and how it operates by now, there are still some important and possibly less familiar nuances that can impact the strength of your patent portfolio over the long term. In particular, it’s important to understand how a company’s own previously filed patent applications can become prior art against later-filed patent applications under the AIA.
This is especially critical for companies who are developing larger portfolios with several patent applications around a core technology area.
To help you navigate the law in this area, let’s take a closer look at how the AIA defines prior art, and then discuss what you can do if a company’s own previously filed application is cited in a rejection against the company’s later-filed applications.
The AIA amended federal statute 35 U.S.C. 102 — which defines what is considered prior art under U.S. law — to effectively create two “buckets” of prior art. These are defined in Sections 102(a)(1) and 102(a)(2) of the statute.
Under both Sections, when you file a new patent application, your company’s previously filed applications can potentially be applied as prior art against the new application. Specifically, if the two applications have similar subject matter, the previously filed application could be used to reject the new application as either being “anticipated by” or “obvious in view of” the previously filed application.
But the AIA also provides exceptions in Section 102(b) for each “bucket” of prior art. In other words, certain types of information may meet the general definitions in Sections 102(a)(1) or 102(a)(2), but are still not considered prior art because they meet one of the specific exceptions listed in Sections 102(b)(1) and 102(b)(2) respectively.
To determine which of the “buckets” your previously filed application might fall into — and whether it qualifies for an exception — use the following table:
Prior art definition
When did the previously filed application become public?
The prior application became public (via publication or grant) before the new application is filed.
The prior application will become public (via publication or grant) at some point — whether before or after the new application is filed.
Who are the listed inventors?
The definition applies regardless of inventorship.
The application must name at least one inventor who’s not an inventor on the new application.
Which statute provides exceptions to this definition of prior art?
Section 102(b)(1) only
Section 102(b)(2) only
How are the exceptions* determined?
1. Earliest date of publication
Ownership of the application
* We’re considering only the exceptions that are most relevant for the scenario considered here. Other exceptions could apply in some limited circumstances.
In short, when you’re developing a strategy for a new application, you may need to take advantage of the exceptions in Section 102(b) if both of the following are true:
Let’s look at when the exceptions apply, how to deal with them strategically when filing an application, and how to invoke them when responding to an office action.
The only exceptions to Section 102(a)(1) are provided by Section 102(b)(1). For sophisticated companies developing large patent portfolios, the exception that is most likely to be useful is the first one, provided in subsection (b)(1)(A) of the statute.
When did the content of the prior application first become public (via publication, patent grant or otherwise)?
If the prior application’s earliest date of publication was more than one year before the effective filing date of your new application, then you can stop there. Any application that was published or patented more than one year before you file your new application is prior art — no exceptions apply.
If the prior application’s earliest date of publication was less than one year before the filing date of your new application, then you might be able to remove the prior application as prior art under the exception provided in Section 102(b)(1)(A).
Section 102(b)(1)(A) provides an exception for a “grace period inventor disclosure,” which is a disclosure made by an inventor within one year before the new application was filed.
In other words, if the material affecting patentability from the prior application was contributed by an inventor on the new application, then that material is not prior art.
There are three possible scenarios:
All inventors from the prior application are also inventors on the new application. Because everything in the prior application was disclosed by an inventor on the new application, you meet this exception — your prior application does not count as prior art.
No inventors from the prior application are also inventors on the new application. Because nothing in the prior application was disclosed by an inventor on the new application, you do not meet the exception — your prior application qualifies as prior art.
Some of the inventors from the prior application are also inventors on the new application. In this case, you have to figure out (if possible) which inventors from the prior application contributed the information that affects the patentability of the new application.
If you haven’t filed the new application yet, and the inventors on the prior application are still with the company, consider adding some of their contributions to the new application so that they can be properly listed as inventors on the new application.
When examining the new application, the USPTO will probably issue a rejection based on the previously filed patent application. To overcome the rejection, you will need to submit a declaration or affidavit (under 37 CFR 1.130) stating that the disclosure in the prior application was made by an inventor on the new application.
The only exceptions to Section 102(a)(2) are provided by Section 102(b)(2). For sophisticated companies who are developing large patent portfolios, the exceptions that are most likely to be useful are the first and third ones, provided in subsections (b)(2)(A) and (b)(2)(C) of the statute.
The prior application meets the exception in Section 102(b)(2)(C) if, as of the filing date of the new application, both the prior application and the new application are owned by (or subject to an obligation of assignment to) your company.
In most tech companies, all inventions would be owned by the company, and all patent applications would be subject to an obligation of assignment to the company. Therefore, unpublished prior applications typically wouldn’t count as prior art due to the exception in Section 102(b)(2)(C).
Make sure to document ownership of all your patent applications in a timely fashion. Otherwise, you may end up creating unnecessary prior art against your own patent portfolio. For one, your inventors should execute assignments when filing patent applications.
For another, your inventors should complete and sign IDRs, which help document the inventor’s obligation to assign the invention to the company. This can be useful if, for example, the inventor leaves the company before they can file a patent application or execute assignments.
Even if you can’t properly document common ownership (or in the event that the two applications are not commonly owned), you can also utilize the exception in Section (b)(2)(A) based on inventorship — similar to the exceptions discussed above for the first “bucket” of prior art laid out in Section 102(b)(1).
When examining the new application, the USPTO will probably issue a rejection based on the previously filed patent application. To overcome the rejection, you need to submit a statement of common ownership.
Specifically, in responding to the rejection, you’ll need to provide a statement that “the disclosure of the subject matter on which the rejection is based and the claimed invention were owned by the same person or subject to an obligation of assignment to the same person not later than the effective filing date of the claimed invention.”
The statement of common ownership doesn’t have to be provided as a formal declaration or affidavit; for example, you can put it in the remarks section of your office action response.
We’ve only discussed previously filed patent applications. If the content of your patent application was also published elsewhere, you will need to analyze that publication separately. In other words, you should be aware of all the ways that the same information may have entered one of the “buckets” of prior art — other than by virtue of being a previously filed application.
Being aware of and citing the most relevant prior art to the USPTO will result in a stronger patent. But in many cases, determining whether something qualifies as prior art and whether your invention is patentable over prior art can require relatively technical analysis.
If you’re looking to move forward with a patent application, consider engaging a patent attorney who’s familiar with your industry. A skilled attorney will be able to tell you the options for dealing with known prior art for your specific circumstance, draft an application that accounts for all known prior art, and keep you on track to meet critical deadlines.
In any case, showing that your invention is different from all prior art is only one of the many factors that will determine the eventual success of your patent application. Download our free checklist now to find out whether you’re really ready to start the patent process — and what to do if you’re still missing a key element.
Prior art is one of the most common reasons the U.S. patent office gives for rejecting claims in patent applications. What should you do if you discover prior art against your invention? Download our FREE eBook to get all the information on this page in a handy PDF.