Inter Partes Review (IPR)

Inter partes review (IPR) is a proceeding before the United States Patent and Trademark Office (USPTO) in which a third party has alleged the invalidity of at least one claim of an issued patent. IPR was instituted by the Leahy-Smith America Invents Act (AIA) and became available to use as of September 16, 2012. Replaces the prior proceeding of inter partes reexamination, for which petitions can no longer be filed. It is meant to be a relatively quick proceeding in that a final determination must be made within a maximum of two years following the filing of the petition, and it includes some minimal allowances for discovery and motions as well as settlement without prejudice.

Filing the Petition

What is challenged and how

A petition for inter partes review must allege the invalidity of at least one patented claim in an issued patent. The grounds for invalidity may be either anticipation or obviousness (§102 or §103), or both, but the scope of prior art is limited to patents and printed publications. Further, the threshold standard for the petition to be granted is the reasonable likelihood of the petitioner’s success with respect to at least one challenged claim. There is a 60-page limit to the petition, and it may include declarations or affidavits.

Who can file

Any person who is not the owner of the allegedly invalid patent and who has not filed a civil action challenging the validity of a claim in the patent may file a petition for IPR. In a suit alleging infringement, counterclaiming for invalidity does not bar the defendant from filing an IPR.


An IPR petition may be filed nine months following the grant of a patent. In addition, if a post-grant review (PGR) proceeding has been initiated on the patent, then an IPR petition may not be filed until the PGR proceeding has been terminated. The nine month waiting period does not apply to any patents ineligible for PGR, for example, those patents issued under the First-to-Invent system.

There is a further requirement when there are concurrent civil or ITC proceedings related to the patent. A petitioner named as defendant in a patent infringement must file a petition for IPR within one year of being served with the summons or else is barred from petitioning for the IPR.

Finally, the USPTO may set an annual limit on the number of IPR petitions for each of the first four years, so a petition must be filed before that limit is reached.


The fee for filing a petition for IPR is $9,000 for challenging up to 20 claims and $200 for each additional claim. If the petition is granted, there is a post-institution fee of $14,000 for up to 15 claims, and $400 for each additional claim.

The Proceeding

The proceeding for an IPR is analogous to a shortened litigation. There is limited discovery and motions, but the entire procedure must statutorily be completed by 12 months from the grant of the petition, with an optional six month extension for good cause. Multiple proceedings on the same patent may be consolidated, stayed, or subject to joinder as the parties request and the Board orders. There is also the option of settlement, which terminates the proceeding with respect to the petition without prejudice.

Preliminary Response by Patentee

Upon receipt of the petition, the patent owner may optionally decide to submit a preliminary response up to three months following the petition date. The response may be in effect a motion to dismiss the petition, giving reasons why no IPR should be initiated, but may not present any new testimonial evidence. In this preliminary response the patentee may also disclaim one or more of the allegedly invalid claims. The response may not amend any of the claims.

Decision on the petition

After filing the petition, a panel of three administrative patent judges (APJs) of the Patent Trial and Appeal Board (PTAB) has a maximum of three months from the filing of the preliminary response or six months from the filing of petition to render a decision on the petition. The decision is based on the petitioner’s reasonable likelihood of success with respect to at least one challenged claim, and may be parsed into separate decisions for each claim and alleged ground of invalidity. To make this determination, the Board may forth an initial claim construction, though this construction is not static and may be challenged or changed later in the proceeding as the parties undergo discovery and file their motions and responses.

If granted, the grant will include a scheduling order setting the timeline for the trial, including the final written decision of the Board. The entirety of the timeline from grant until final written decision must be no longer than 12 months, though extensions of up to six additional months are allowed for good cause.

If the petition is denied in whole or in part, the petitioner may request a rehearing before the Board but there is no appeals process through the courts.


Discovery in proceedings before the PTAB are much more limited than discovery in district court proceedings. Generally the following procedures are allowed in IPR proceedings, but the scope of discovery may be a subject of agreement between the parties:

  • Initial disclosures – names of potential witnesses, copies of all documents used by a party to support its arguments
  • Production of any exhibit cited in a document or testimony
  • Production of relevant information that is inconsistent with a position taken
  • Cross-examination (depositions) of declarants
  • Testimony can be compelled
  • Additional discovery can be requested if it is “in the interests of justice”

Discovery time limits will be set by the Board in the order granting the petition, but will only be a few months at most for each stage so as to complete the proceeding within the 12 month timeline. A sample discovery timeline is given here:

0 Months (grant of petition)

0-3 Months Discovery by patent owner

3 Months Patent owner’s response, and optional motion to amend claims

3-6 Months Discovery by petitioner

6 Months Petitioner’s reply, and possible opposition to motion to amend

6-7 Months Discovery by patent owner

7 Months Patent owner’s reply

8 Months Oral hearing (if requested by either party)

8-12 Months Decision by Board

Confidential Information

The file of an IPR is generally open to the public. However, the AIA provides for one or both parties filing a motion to seal for good cause. Further, the AIA provides for protective orders to govern the exchange and submission of confidential information.


The petitioner and patent owner may settle the issue between themselves, and may submit the settlement and a motion to terminate the proceedings to the Board at any time prior to the final written decision by the Board. Generally the proceedings will terminate following settlement, but termination is discretionary and the Board may continue the proceedings and determine issues of patentability after the parties have settled.

Decision by the Board

After discovery has finished, the matter is submitted to the Board for a decision. This process may still involve motions to exclude evidence (generally on the same grounds as in district court litigation), requests for an oral argument, or other procedural matters. The process may also involve an oral hearing, if one is requested by either party, before the three-judge panel.

The final decision of the Board must be delivered in a written decision within the time limit of 12 months from institution of the IPR, unless a proper extension (up to six months) was granted.

Dissatisfied parties may request a rehearing with a specific identification of the issue(s) misunderstood or overlooked by the Board.



The decision of the Board may be appealed by either party to the Court of Appeals for the Federal Circuit within 63 days of either the final written decision or the decision on rehearing, if applicable.


Estoppel attaches to the petitioner upon a final written decision by the Board, regardless of any appeals which may be filed. However, if the parties settle during the course of the proceeding and terminate the IPR before a final written decision is delivered, no estoppel will attach.

The estoppel that attaches is slightly different with regards to proceedings before the USPTO and in civil and other litigations:

Estoppel may also attach to the patent owner. Following the final written decision by the Board, the patentee may not take any action inconsistent with any adverse judgment, including obtaining in a patent a claim which is patentably indistinct from a refused or cancelled claim or amending its specification or drawing in a way that it was denied during the proceeding.

The petitioner in an IPR proceeding of a claim in a patent in which a final written decision has been rendered, nor a real party in interest or privy of the petitioner may not…


request or maintain a proceeding before the USPTO with respect to that claim

District courts and ITC:

assert either in a civil action or in a proceeding before the ITC that the claim is invalid

…on any ground that the petitioner raised or reasonably could have raised during the IPR

Practice Tips

  • The standard for invalidity before the PTAB is “preponderance of the evidence” unlike the “clear and convincing” standard used in district courts.
  • The USPTO applies the broadest reasonable construction of claims.
  • There is no presumption of validity in proceedings before the USPTO.
  • IPR discovery is much more limited than what is available in district court, making the proceeding generally a cheaper alternative for clients.
  • At this point, it is unclear as to whether estoppel attaches only to the reviewed claims in the patent at issue, or if it also covers unreviewed claims which raise common issues. Relatedly, the actual extent of “reasonably could have raised” is also unclear.
  • Lead counsel for IPR proceedings must be a registered patent attorney, but because of the discovery and litigation aspects, it will probably be helpful to engage an experienced litigation attorney as well. Keep in mind this is fundamentally a Patent Office proceeding.
  • Filing a civil action claiming invalidity bars someone from petitioning for an IPR, but filing for a declaratory judgment of non-infringement does not have the same effect, even if a counterclaim for infringement is answered by an affirmative defense of invalidity. SeeAriosa Diagnostics v. ISIS Innovation Ltd. (Patent Trial and Appeal Board, Case IPR2012-00022, Paper 20, Decision regarding standing to file).

Inter Partes Review (IPR) Fast Facts

What is challenged?
  • Must allege invalidity of at least one patented claim
  • Invalidity based on §102 or §103, using patents and printed publications
  • Threshold standard to institute is likelihood of success on the merits
When can you file?
  • The later of 9 months following the grant of the patent or the termination of a PGR proceeding, if applicable
  • No later than one year following service of a summons in a suit for infringement
Who can file?
  • Any non-owner of the patent who has not filed a civil action claiming invalidity and who is not subject to estoppel (see below)
What are the fees?
  • To file: $9,000 for up to 20 challenged claims, $200 per additional claim
  • Post-institution: $14,000 for up to 15 claims, $400 per additional claim
Timeline for proceeding
  • Maximum 6 months from filing to decision on the petition
  • If granted, 12 months from date of institution until final written decision by the Board
  • 6 month extension possible for good cause
  • More limited than in district court proceedings
  • Parties may mutually agree to an increased scope
  • The parties may settle and submit a joint motion to terminate without prejudice
Board’s decision
  • Standard is preponderance of the evidence
  • Applies broadest reasonable construction of the claims with no presumption of validity
  • Rehearing of the final decision may be requested by either party
  • Decision may be appealed to the Federal Circuit
  • Attaches upon final written decision
  • Petitioner nor real party in interest may not request or maintain a proceeding before the USPTO with respect to the challenged claim or assert in a civil action that the claim is invalid on any ground that the petitioner raised or reasonably could have raised
  • Patent owner may not take any action inconsistent with an adverse judgment

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