While there are others, a non-inclusive list of legal defenses to a charge of patent infringement include invalidity, non-infringement, inequitable conduct, public disclosure or sale of the invention well before the filing date, patent exhaustion, laches, equitable estoppel, and prosecution history estoppel.
INVALIDITY
When attempting to invalidate a patent, you will start from a disadvantage, as issued US patents are presumed to be valid. This means that you, as the one accused of infringement, will have the burden to show why the issued patent is invalid. To do this, you must put yourself in the shoes of a patent examiner examining the patent. Just because one patent examiner granted your competitor a patent does not mean a court will find that patent valid. The patent examiner could have been sloppy. It will be incumbent upon you in this position to scrutinize the patent examiner’s work. Did he or she miss some prior art (existing technology) that was out there, and that would have prevented the claims from issuing? Did he or she have the right prior art, but not apply it properly to your competitor’s claims when the patent was being examined? Did he or she grant a patent on claims that were directed solely to an algorithm or some other subject matter that courts have found to not be patent eligible? Are the claims in the issued patent not enabled by the patent’s main disclosure? These, and more, are all reasons that could be used to invalidate a patent. A good question to ask in assessing whether a patent is valid is, “Does the patent satisfy 35 USC 101, 102, 103, and 112?” More information on this can be found in my article, “How do I get a patent?” Determining that at least one of these four statutes is not satisfied will prove invalidity. If you are unsuccessful in establishing that the patent is invalid, this does not mean that you will be on the losing side of this litigation in any respect.
NON-INFRINGEMENT
More specifically, even if the patent is valid, in order for your competitor to succeed against you, he or she has the burden of proving that your acts infringe one or more claims of the patent. Many times people make a charge of patent infringement against someone, and it very well turns out to be that that someone is not actually infringing the claims of the asserted patent. What the accuser has to show is that you have used, manufactured, imported, and/or sold the invention, as covered by the claims of the patent, without the patent owner’s permission. Stated differently, your competitor has to show that each and every element of a claim is found in your product, or your methodology, or your system. If any element of the claim is missing in your product, methodology, or system, you would not be infringing that claim. As such, when you are assessing whether or not you actually infringe your competitor’s patent, you will have avoided infringement if at least one element from each claim is missing in your product, methodology, and system. How might this play out? A claim (these are the numbered, and less readable statements found at the very end of utility patents) in a patent might say: “What is claimed is a phone having a body, a touch screen interface located on the body, and a volume adjustment system located on a side portion of the body.” If you are selling phones with touch screen interfaces, but no volume adjustment systems, you would be in the clear. Stated differently, the claim of the patent must have several items (phone, body, touch screen interface, and volume adjustment system), and your alleged infringing phone does not have all of those items, resulting in you not infringing the claim of the patent.
INEQUITABLE CONDUCT
In addition to invalidity and non-infringement, asserting that there was inequitable conduct when the asserted patent was procured could also help you escape liability. Regarding inequitable conduct, a principal duty that applicants have when seeking a patent is to deal honestly with the USPTO. If you can somehow establish that your competitor did not deal honestly with the USPTO when he or she procured the patent, you will likely have avoided that patent. Establishing inequitable conduct can be done in several ways, including proving that your competitor either misled the USPTO somehow (e.g., in an amendment filed during prosecution, did he or she lie to the patent examiner about what a piece of prior art said?), and/or proving that he or she did not satisfy his or her duty of disclosure to the USPTO. During prosecution of a patent application, all people associated with its filing (e.g., attorneys, inventors, etc.) have a duty to disclose to the USPTO any prior art (existing technology) that they are aware of which is material to the patentability of the claims they are seeking. In other words, they are legally obligated to tell the USPTO all of the technology that is close to the technology they are filing on. If you can show that they were aware of some prior art that was material to patentability, but that they failed to disclose it (e.g., in an information disclosure statement, background of the application, or otherwise), you will might have a case of inequitable conduct. Finally, to establish inequitable conduct, it must be proved that the pertinent action or inaction materially affected what happened at the USPTO, and that the action or inaction was done with the intent to deceive the USPTO.
PUBLIC DISCLOSURE OR SALE
Another way in which you could defend yourself is to show that the invention, as covered by the claims of the asserted patent, was publicly disclosed or sold more than one year before the filing date. In the United States, if an invention is sold or publicly disclosed more than one year before its filing date, no patent can issue on that invention. It is important to note that the filing date of a patent is often not the date on which the non-provisional patent application was filed. Rather, if the non-provisional patent application claims priority to an earlier provisional patent application, and a public disclosure or sale only happened 10 months before the filing date of the provisional patent application, and 16 months before the filing date of the non-provisional application, this defense would generally not be applicable to you. However, if you are being thorough, you will want to read, with precision, the claims of the final asserted patent, and compare them to the disclosure of the provisional patent application. If those claims are not enabled (supported) by what was disclosed in the earlier provisional patent application, they will not be entitled to its filing date, and as such may be barred by an earlier public sale or disclosure. For more on this, please see my article entitled, “What considerations should I have in mind before I file for a patent and what is a provisional patent application?” It is very common that non-provisional patent applications add new subject matter that was not present in the provisional patent application. Studying the provisional patent application in this manner, something patent examiners generally don’t not, could also reveal that some new prior art should be considered, because the filing date for at least some of the issued claims is no longer the date the provisional application was filed, but is now the date the non-provisional application was filed. Perhaps this new prior art might invalidate the patent under 35 USC 102 and/or 103.
FIRST SALE DOCTRINE
Moreover, if you are reselling a product, this may allow you to escape liability. This is known as the first sale doctrine, and it generally provides that the first sale of a product exhausts at least some of the patent owner’s rights. What this means is that purchasers of patented items generally are permitted to use and resell the product as they wish (e.g., they cannot be found to infringe the patent on the product). This defense is not a statutory one, but rather is grounded in common law.
LACHES
In simple terms, this defense says you could escape infringement liability if the patent owner has taken too long to take action against you. Once a patent owner becomes aware of infringing acts, any lawsuit that he or she files for patent infringement must occur within a reasonable time, otherwise the doctrine of laches may bar his or her suit. Elements for laches include a patent owner knowing of infringement, unreasonably delaying in taking action, and causing direct prejudice to the accused infringer as a result. This may present as an accused infringer not knowing that he or she is infringing someone’s patent, taking actions to build their business, and continuing to do so because there has been no action from any patent owner. It could also present as people forgetting what happened in the distant past, people relevant to the case passing away, or information being lost. This defense, if proved, could eliminate damages in an infringement lawsuit.
EQUITABLE ESTOPPEL
Furthermore, if there has been a long period of inactivity by your competitor, and then you are faced with a charge of infringement, equitable estoppel could escape you from liability for infringement. This may present as the patent owner being misleading, the person accused of infringement relying on the patent owner’s actions, and prejudice resulting from any potential action by the patent owner. For example, if the patent owner reasonably causes the alleged infringer to believe that he or she does not intend to enforce the patent, and then subsequently tries to enforce it, this would be misleading. If you, as the accused infringer, were to have relied on this, and would be prejudiced by action by the patent owner, then defending yourself via equitable estoppel may be a good idea.
PROSECUTION HISTORY ESTOPPEL
Finally, and a bit more technical, is prosecution history estoppel. If you have reviewed the file wrapper (e.g., the patent’s entire USPTO history) of the issued patent, and you notice that there were narrowing amendments made to the claims during prosecution, this fact may preclude the patent owner from invoking what is called the doctrine of equivalents. If the patent owner cannot do this, then he or she would not be able to broaden the scope of their claims to cover subject matter ceded by the amendments. This could be very good news for you. It could be a way to bring your accused device outside of the scope of the claims of the patent. If, however, no narrowing amendments were made to the claims, then this defense would not be applicable.
In sum, there are many defenses which can protect someone from a charge of patent infringement. A few of them are invalidity, non-infringement, inequitable conduct, public disclosure or sale of the invention well before the filing date, patent exhaustion, laches, equitable estoppel, and prosecution history estoppel.
This article was authored by John P. Powers, is intended to keep readers current on matters affecting intellectual property and is not intended to be legal advice. If you have any questions about its content, please leave a comment below.
©John P. Powers, 2021, all rights reserved.