What Is an Inter Partes Review?

An inter partes review is a trial held before the Patent Trial and Appeal Board that determines whether a given patent is valid. Filing an inter partes review (IPR) means that you are challenging an existing patent. Reviews are held before the Patent Trial and Appeal Board (PTAB). Any person other than the patent owner is eligible to file for a review. You can only file for a review if you find grounds in §§ 102 or 103 or if you find a basis in prior art or patent publications. 

Every type of patent is eligible for review. This includes first-to-invent and first-inventor-to-file patents. Petitions for first-inventor-to-file patents cannot be filed until nine months after a patent has been approved or renewed or until after the end of a post-grant review. There are no such deadlines for first-to-invent patents. The person who owns the patent has the opportunity to respond. 

A review will take place if the person challenging the patent has a chance to win their claim. Decisions will usually be made within the year. Rules for inter partes review were established on September 16, 2012, and apply to any patents issued before, on, or after that date.

Inter Partes Review vs. Post Grant Review

Inter partes review was established by the America Invents Act (AIA). However, there are some limitations to the review process. All patents are subject to a ninth-review period. Patents can be challenged during this review period. IPR review is only allowed after these nine months have expired. This does not apply to first-to-invent patents. 

Most people confuse post-grant reviews and inter partes review despite their differences, which include the following:

  • IPR is available for all patents, regardless of priority date.
  • An IPR must be filed within one year after an infringement complaint has been served.
  • The standard of proof is different. You must prove a reasonable likelihood that you will win at least one claim before being approved for IPR. For post-grant review, you must prove that at least one challenged claim is more likely than not to be deemed unpatentable.
  • During IPR, "prior art" is limited to patents and printed publications. Patents can be challenged on any grounds during post-grant reviews.

In post-grant reviews, it's possible third parties will be prevented from raising an invalidity defenses. Inter partes review has a legal estoppel that is equal with the estoppel for inter partes reexamination. Even if a third party has taken advantage of inter partes review, they can still bring their case to other legal forums. The grounds they can use include everything except those that were used or could have been used during inter partes review.

Basic IPR Statistics

IPR has been a very popular option for challenging patents since it was created in 2012. In the fiscal years 2013 and 2014, there were 361 decisions on IPR requests, with a total of 288 IPR trials granted. This means that the PATB frequently approves petitions. This is beneficial for those considering challenging a patent. 

The first year that IPR was available, 87 percent of petitions were granted. This approval rate was 74 percent between 2013 and 2014, 65 percent between 2014 and 2015, and 66 percent between 2015 and 2016. Between 96 and 184 petitions are filed each month, which is 400 to 450 per quarter. 

Once they reach trial, IPRs tend to be decided in favor of the petitioner. For instance, 40 trials that were held in March of 2016 decided that all claims were not eligible for patent. Appeals have also increased by a large degree. In 2016, there were between 600 and 700 IPR appeals. 

Filing a Petition

There are several steps for filing an IPR petition. First, you must file within the right time frame. After an infringement complaint has been filed against you, you have one year to file your IPR petition. This is outlined under 35 U.S.C. 315(b). 

Second, your petition must comply with these conditions:

  • You must pay the required fee of $9,000. If a full review is granted, you will owe $14,000.
  • Your petition should name every interested party.
  • Each challenged patent must be listed. You should also include the reasons for your challenge. 

Your petition needs to include evidence of your claim. Evidence can include the following:

  • Printed publications and patent copies.
  • Affidavits for expert opinions.
  • Any other information requested by the PATB Director.
  • Documents required for the patent owner. 

Civil claims are automatically stayed when an IPR is filed. Counterclaims can continue. After a decision has been reached, you cannot request another review on the same grounds as your IPR or on grounds that could reasonably have been raised during your IPR. You will also be limited in your options for civil claims with the United States International Trade Commission. 

It's possible to reach a settlement with the patent owner. Settlements must be submitted in writing to the PTAB. If the PTAB accepts the settlement terms, the IPR will be canceled. There are no limits to civil action after a review has been terminated. 

You also have the right to appeal any decision in your IPR. Anyone involved in the IPR must also be involved in the appeal. 

It should take about six months before a decision about your petition has been reached. Trial decisions can take as long as a year. Appeals can add as much as three months to the process. 


When a petitioner requests an inter partes review of a patent claim and receives a written decision, they cannot request a hearing with the USPTO for the same claim on any grounds that were raised or could have been raised during the inter partes review. This is known as an estoppel provision. There is also an estoppel against the petitioner or other interested party for civil actions in certain cases that take place before the United States International Trade Commission and result in a final written decision. 

It's possible to be permitted additional motions to amend the claims. However, this must be a joint claim made by the petitioner and patent owner in an effort to reach a settlement. 


Inter partes reviews can be ended when jointly requested by the petitioner and the patent owner. However, if the USPTO has ruled on the merits of the review before the termination request is filed, the review will continue. Any agreement or understanding to end an inter partes review must be submitted in writing. A verified copy of the agreement must be submitted to the USPTO before the termination will be granted. 

When an inter partes review is terminated with respect to the petitioner, the petitioner will not be subjected to estoppel based on their inter partes review request. When no petitioner is left in a review, the USPTO can either terminate the review or continue to a final written decision.

Patent Owner Rights

Patent owners can immediately respond to your petition. This response will explain why no review should be granted. Responses must be filed within three months after the IPR petition has been given a filing date. The preliminary response may be waived by the patent owner to speed up the IPR process. Responses cannot include new evidence. 

Patent owners can request a motion to amend their patent. This must take place before the patent owner response has been filed. Amendments can be denied if it directly addresses the challenge. Enlarging the scope of the patent or adding new information are also grounds for denial. If an amendment is granted, it can cancel the IPR request. 

IPR and Property Rights

Inter partes reviews are not without controversy. In particular, patent holders claim that dealing with these reviews is an unfair burden. Some patent holders have reported that facing an IPR has affected their stock prices. 

It has been claimed by some that removing a patent through the IPR process violates property rights under the Takings Clause. However, no Supreme Court decision has ever stated that patents count as property under the Takings Clause. However, they did rule that patents do count as property in Florida Prepaid Postsecondary Education Expense Board v. College Savings Bank. 

Still, there is no method for patent owners to receive compensation under the Takings Clause for infringement. Courts have not generally considered patent proceedings to be subject to the Takings Clause. With regulations like the America Invents Act (AIA), the Supreme Court will often consider IPR a method of correcting problems with the administrative system rather than a violation of property rights. 

Even if the AIA and IPR process weakens patents, there is no reason to believe it violates a patent holder's constitutional rights. 

Patent Trial and Appeal Board

When you file a petition for an IPR, the proceedings will be handled by the Patent Trial and Appeal Board (PTAB). The PTAB is made up of administrative law judges. These judges will determine whether your request for review is valid, make rules for discovery, and provide a final ruling. During the trial, you must prove unpatentability by "a preponderance of the evidence."

If a review is granted, the PTAB may narrow the scope of your claim. They will provide an intricate decision about the eligible grounds in your case. Once your review has been granted, the PTAB will lay out a schedule for the next year. Your case may also be extended by six months if necessary. 

Most schedules will allow the patent owner three months for discovery. During discovery, the patent owner may gather depositions or other pieces of evidence. After discovery, there will usually be a month-long period where motions can be filed. The oral hearing will be next on the schedule. Once oral hearings are completed, the PTAB will reach a decision. 

The Supreme Court and IPR

Recently, the IPR rules established by the American Invents Act were affirmed by the Supreme Court. This occurred at the conclusion of Cuozzo Speed Technologies, LLC v. Lee. Two important issues were addressed during this case. The first was whether IPR decisions could be appealed in federal court. The second was whether the PTAB was using reasonable rules for determining claims. 

On both issues, the Court found in favor of the PTAB. In regards to appeal, the Court found that the language used in the AIA is very clear and that appeals were specifically not allowed. They also found that allowing appeals would undercut the intent to give the Patent Office more power. 

On the second issue, the Court decided that using the broadest reasonable construction to decide IPR hearings was within the authority of the PTAB. Using a previous decision, it was determined that when there is a gap in rules, an agency has the power to enact their own rules. It was also noted that the patent office has been using broadest possible construction for more than 100 years. 

Frequently Asked Questions

  • When should I use an inter partes review?

An inter partes review should be used when you have grounds to challenge a patent. These grounds should be based on prior art or patent publications.

  • Who can file a review?

Anyone is eligible to request a review. However, you must have a likelihood of winning at least one claim.

  • Are there time limits?

Yes. Petitions must be filed within a year of infringement claims. You will need to wait nine months for first-to-file patents.

  • Can I file a civil claim?

No. An IPR review cancels a civil claim. After an IPR decision has been reached, you are usually not allowed to file additional claims.

  • Do I need an attorney?

Yes. Consulting an attorney is always a good idea. An attorney can tell you if you have grounds for an IPR hearing. They can also help you gather any evidence needed to prove your claim. 

Hire an UpCounsel Attorney

Requesting an inter partes review is a very complicated process. If you're not familiar with the steps for petition, your review may be denied. To get help with your inter partes review, you should hire an experienced attorney from UpCounsel

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