How to defend your patents at the PTAB

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Proceedings and recent statistics

Since their introduction in September 2012, inter partes reviews and post-grant reviews have been extremely popular vehicles for challenging a US patent. These proceedings allow anyone other than the patent owner to challenge the validity of an issued patent before the PTAB at the USPTO. The proceedings, which are functionally trials on paper, take about six months if the petitioner fails to get a trial instituted, and about 18 months if the petitioner succeeds. To date, more than 12,000 inter partes reviews and more than 300 post-grant reviews have been filed.

Patent owners are concerned about these proceedings and for good reason. Although the numbers have improved since the mid-2010s, in the past five years the PTAB has, on average, decided to institute a post-grant trial about 60% of the time. For claims that reach a final written decision, about 60% are found to be unpatentable. Patent owners should be aware of these proceedings and do what they can before, during and after a PTAB proceeding to retain their patents.

Defending a patent before a PTAB proceeding starts

Patent owners should position themselves for victory at the PTAB by taking preventative measures when drafting and prosecuting their patent applications. Doing so can result in important tactical advantages if the patent ultimately ends up before the PTAB.

Drafting an application with an eye on later challenges

Choices made when drafting a patent application can have significant ramifications when trying to defend the patent later on in a post-grant proceeding. Some applicants submit a bare minimum disclosure when seeking a patent, which may be to keep costs down or for tactical reasons. But it can be beneficial to include as much detail about the invention as possible in an application for a number of reasons:

  • za more robust application provides more options if an amendment is required in a later post-grant proceeding; and
  • za more detailed description lessens the opportunity for challenges based on formalities related to disclosure failures (eg, an inadequate written description or lack of enablement).

When drafting, consider having claim sets with broad coverage, narrow coverage and options in between. The medium and narrow claims are less likely to suffer from patentability attacks and narrow claims are most likely to survive. If necessary, a patent owner can disclaim the broadest claims (thereby curtailing the expensive full PTAB trial process) or can narrow the broadest claims using support for the full claim set.

Another consideration relates to claim construction. Many of the big fights in post-grant proceedings relate to how one or more terms in the claims at issue are defined. Typically, a challenger seeks to have claim terms defined fairly broadly to encompass prior art, while the patent owner will seek a narrower definition to avoid the prior art while still capturing an accused infringing device. The PTAB does not have to adopt either proposed definition and is free to make its own based on the evidence before it. Claim construction is also statistically one of the most overturned issues on appeal. So, having clarity in this area is useful – unambiguous definitions of claim terms can provide more certainty in the proceeding’s outcome.

A patent owner can help its own cause by providing clear definitions in the application. This is particularly true when the claims include an uncommon word or phrase or terms that are open to multiple interpretations. Under certain conditions, a clear and unambiguous definition in the application is binding for claim construction purposes. That certainty may help reduce the pool of prior art that could be used to challenge the patent, or it may clarify the chances of success in a challenge. At the very least, there is one fewer issue to consider in the post-grant proceeding so that arguments can be more appropriately focused.

Examination strategies

During examination of a patent application, examiners will most commonly assert that an invention is obvious (ie, that it did not exist before, but it would not have taken an inventive leap to get there based on existing information). An applicant’s typical response is either to argue that the patent examiner is wrong or to amend the patent claims to add distinguishing features. An applicant can also submit evidence of objective indicia of non-obviousness (sometimes referred to as ‘secondary considerations’). This evidence relates to several judicially recognised factors that tend to show that an invention is not actually obvious, such as:

  • zcommercial success of the invention;
  • zunexpected results;
  • zthat the invention resolved a long-felt but previously unmet need;
  • zfailure of others; and
  • zcopying of the invention.

An applicant may omit this evidence on occasion because:

  • zit can be time-consuming to acquire and assemble the necessary information;
  • zit can be difficult to prove; and
  • zit is often simpler to argue or amend.

But getting the patent examiner to analyse secondary consideration evidence on the record, even if unnecessary to overcome a rejection, can strengthen the patent against later-filed obviousness challenges. The PTAB has discretion when considering a post-grant petition to rely on the findings of the examiner during the patent application process. An examiner’s determination that the secondary consideration evidence is persuasive may influence the PTAB to reject a later challenge as unlikely to succeed. It is in the patent owner’s interest to submit this evidence early.

Patent owners are also usually reticent to discuss prior art in detail during examination – they try to avoid unnecessarily limiting statements. But that practice may also need refinement.

Challengers can rely on prior art previously of record by arguing that the examiner overlooked something in a reference or by viewing the art in a different light. A more thorough discussion of a reference and its relation to the claimed invention, particularly if the examiner is mistaken in some way, makes it much harder for a challenger to contend that the examiner made an error. The result is that the challenger may have to look elsewhere for prior art deemed ‘better’ than what was of record, which may be difficult.

The application ‘family’

Multiple patents can be obtained from a single original patent application (known as ‘continuations’ or ‘divisionals’). Challenging a patent at the PTAB can be very expensive – the USPTO filing fees alone start at $41,500 for each disputed patent. Patent owners can use these two facts to their advantage. By obtaining multiple patents and creating a ‘family’, it becomes increasingly costly for a challenger to mount an entirely successful attack. The more patents, the more chances that one or more potentially valuable claims will survive.

When possible, it is also advisable to keep at least one patent application in the family pending before the USPTO (ie, in the examination process). If an earlier patent in the family is challenged, the patent owner can take the arguments or prior art from the challenge and submit them to the examiner. The idea is to navigate these grounds with the examiner to arrive at an allowable claim set for the pending application. The new patent will now be highly insulated from the same attack that the challenger used on the earlier patent, potentially limiting the challenger’s options with respect to the new patent.

Defending a patent during a PTAB proceeding

There are several key events and issues during a PTAB proceeding that allow a patent owner to greatly increase their chance of success. These include the preliminary response stage, using experts, the oral hearing, motions to amend and deciding whether to settle.

Preliminary response considerations

Patent owners are permitted, but not required, to submit a preliminary response approximately three months after a petition has been filed. Patent owners are permitted to support their preliminary response with an expert’s declaration. Until recently, this was not a particularly fruitful exercise because the PTAB was obliged to resolve any factual disputes in favour of the petitioner at the institution stage. That rule changed in 2020, so filing a preliminary response can now be an effective way to vet one’s initial theories and either convince the PTAB not to institute a trial or, if a trial is instituted, to get the PTAB’s initial views on the proposed arguments. There is generally very little interaction with the PTAB once a trial is initiated, so learning from the PTAB what they do and not agree with can really help re-focus a patent owner’s arguments.


Experts are a must in post-grant proceedings for all but possibly the very simplest cases. The power of an expert’s testimony to influence the PTAB’s final decision necessitates great diligence and care by the patent owner when selecting that experts. The expert must be competent to testify about the subject matter of the patent, but the closer the expertise gets to the low-level details of the patent the better. For example, an electrical engineer may be able to testify about semiconductor structures in general. However, if the patent is directed to details at molecular level rearrangements during doping procedures, a specialist in that area may be better equipped to convince the PTAB of the patent owner’s arguments. It is also important to find an expert with testifying experience or the ability to endure cross-examination. Although there is generally no live testimony before the judges in a PTAB proceeding, the patent owner’s expert will be deposed.

The expert’s testimony on behalf of the patent owner comes in the form of one or more declarations submitted along with the patent owner’s preliminary response before institution and the patent owner’s response during the proceeding. A patent owner should have its expert lay out all the opinions necessary and their bases in the declaration, including any reasonably foreseeable rebuttal arguments, because while the patent owner typically gets a sur-reply as of right, a new declaration is generally not permitted. Patent owners should also be careful to make sure that the expert declaration provides evidentiary support (eg, supporting documents or data) for as many statements as possible, rather than simply stating perfunctory conclusions. PTAB judges want to see reasoned analysis from an expert, not just a parroting of the attorney arguments in the briefings.

Oral hearing

Towards the end of the proceeding, both the patent owner and petitioner have the ability to present their arguments to the three-judge panel deciding the case. Before this hearing, both sides have the opportunity to prepare and serve demonstrative exhibits, which can be great tools for summarising voluminous and complicated information. Patent owners should devote time and resources to having a very strong set of demonstratives. The counsel for the patent owner should also be completely familiar with the entire record and ready to face difficult questions from the judges. The hearing may be relatively brief (the PTAB often limits the hearing to between 30 and 60 minutes), but the judges come prepared and pose thoughtful questions. For judges on the fence about one or more issues, the hearing is often when they make up their minds.

Motions to amend

Another key moment in the proceeding is the time for making a motion to amend, should the patent owner wish to do so. The PTAB now offers patent owners the ability to get preliminary guidance from the judges on a proposed amendment, which can be a great resource. While taking advantage of this option makes the remainder of the schedule quite tight, it can increase the patent owner’s chances of the motion succeeding. While patent owners would typically like their original claims to stand, the high ‘kill rate’ for claims reaching a final written decision cautions against being too cavalier.

Settlement considerations

The parties can settle inter partes reviews and post-grant reviews, but even if the parties elect to do so, the PTAB can continue the proceeding in the petitioner’s absence. The PTAB rarely does this, but it is a reality of which patent owners should be aware. The sooner in the proceeding that the parties settle, the more likely it is that the PTAB will not continue the proceeding. Patent owners should seriously consider settlement immediately after the petition is served, after the decision to institute issues and before the oral hearing.

Low appeal success demonstrates importance of time

Patent owners must make the most of their time before the PTAB because appeals from inter partes reviews and post-grant reviews are rarely successful. In about 74% of cases, every issue addressed at the PTAB is affirmed by the US Court of Appeals for the Federal Circuit, which has exclusive jurisdiction over these appeals. About 10% of cases have a mixed outcome and only about 13% of cases have every issue reversed or vacated. To add insult to injury, the Federal Circuit issues a Rule 36 affirmance – wherein the appeals court offers no additional opinion and simply affirms the PTAB’s actions in one sentence – in roughly 44% of cases.

This means that patent owners must maximise their chances of success while before the PTAB. Patent owners should consider settlement early and periodically throughout the proceeding, as reaching a business solution with the petitioner may help in the long run. Patent owners electing to fight should:

  • ztake the petition seriously;
  • zhire one or more experts as soon as possible and rely on them to dissect and counter the petitioner’s arguments;
  • zbe clear and thorough in their pleadings;
  • zraise known issues and preserve them for appeal;
  • zcreate a complete record for the Federal Circuit’s attention; and
  • zbe effective at the oral hearing.

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