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How To Join an IPR—And Why You May Want To

Inter partes review has become a popular vehicle to challenge patents. An IPR’s shortened timeline and expense, relative to litigation, makes it a viable tool for defendants in infringement actions if filed within the statutory 12-month window. An IPR petition can also be accepted outside of this window if a joinder request is filed within one month of an earlier IPR’s institution. Given the benefits of IPRs and the desire to keep an IPR alive before the petitioner settles out of litigation, joining an instituted IPR can provide a strategic advantage.

Under 35 U.S.C. Section 315(c), after an IPR is instituted, the Patent Trial and Appeal Board (PTAB) may join a petitioner in a subsequently-filed IPR “that the director, after receiving a preliminary response under section 313 or the expiration of the time for filing such a response, determines warrants the institution of an inter partes review under section 314.” The PTAB evaluates joinder requests on a case-by-case basis and can consider a number of factors in addressing whether joinder is appropriate. Under 37 C.F.R. Section 42.122, a request for joinder must be filed within one month of the institution date of the IPR for which joinder is requested.

The PTAB evaluates four factors in determining joinder: (1) why joinder is appropriate; (2) any new unpatentability grounds; (3) joinder’s impact on the existing IPR; and (4) simplification of briefing and discovery in the joined proceedings. Joinder requests may be denied for deficiencies in any of these factors. A critical factor is the effect on the existing IPR’s schedule, which arises from the PTAB’s statutory obligation to resolve IPRs within one year of institution and provide the “just, speedy, and inexpensive resolution of every proceeding.”

New Arguments and Evidence

Joinder is more likely if the arguments and evidence are the same as the existing IPR. While joinder has been granted despite the introduction of new arguments or new evidence, the PTAB has also declined to join petitions when the impact is not justified. The PTAB has expressed concerns that new arguments or evidence could complicate the joined proceedings. However, joinder may still be granted if the petitioner identifies the differences and can explain that joinder will not lead to delay or prejudice to the existing parties.

For example, joinder was granted although the “grounds and arguments are substantially different (anticipation versus obviousness) and the principal pieces of prior art are different,” when the petitioner explained the overlap between the prior art references and the ability to modify the IPR schedule to allow the patent owner additional time to respond to the new grounds and conduct additional discovery. The PTAB has also allowed the introduction of new anticipation arguments when the additional impact over the existing obvious arguments is shown to be minimal. However, failure to justify the introduction of new evidence and arguments can be grounds for rejection.

Petitioners seeking to join one of their own earlier-filed IPRs must take care to avoid the new petition appearing to be a “second bite at the apple” or a mechanism to avoid the page limits. For example, the PTAB has denied joinder when a petitioner has not explained why its own earlier-filed IPR could not have included the new arguments or prior art.

In any event, the availability of such types of joinder is in question due to an unresolved split regarding whether Section 315(c) even allows joinder of parties and issues.


Joinder is more likely if the expert and the content of the expert declaration are the same as that in the existing IPR. Alternatively, a subsequent agreement to use the same expert may eliminate objections regarding any impact on the schedule, especially where the new petition is restricted to the same grounds of invalidity as the original petition. The mere use of a new expert, even if the expert’s conclusions are identical to those of the expert used in the earlier-filed IPR, may be enough for the PTAB to reject a joinder request if doing so would complicate the existing IPR by requiring another deposition and more discovery.

Proposed Schedule and Simplification

As part of the joinder motion, it is important to provide a schedule and discovery plan that does not unduly extend the schedule or increase the amount of discovery, especially if seeking to add new arguments or prior art. It is helpful if the petitioner obtains agreement on the schedule, discovery and roles from the existing parties to the IPR, although such agreement may not be sufficient. In one case, the PTAB noted that the joinder request did not set forth how briefing and discovery could be simplified upon joinder or whether the existing petitioners had agreed to work with the new petitioner to coordinate discovery. The PTAB found these shortcomings problematic given the new arguments and evidence the petitioner sought to include and denied joinder.

Successful strategies to avoid concerns of schedule impact and increased discovery burden, especially without an agreement from the existing parties, include an offer to take on an “understudy” role or consolidated filings and to adhere to the existing schedule. For example, over the original petitioner’s and the patent owner’s oppositions, the PTAB granted joinder where the petitioners proposed such an arrangement and did not raise any new issues. As an “understudy,” the new petitioner would only assume the first chair role in the event that the existing petitioner settles. Such an “understudy” role often includes an agreement not to submit separate papers, pose questions at depositions, or present oral argument at the hearing or, alternatively, for the parties to designate attorneys to present a consolidated argument with deference to the earlier petitioner.

The best chance of success, when seeking joinder with another party’s IPR, is for the petitioner to file an identical petition using the same expert or agree to take an “understudy” role. While lacking the ability to add new arguments or prior art or to file an improve expert declaration, these restrictions may still be preferable when a defendant finds itself outside of the 12-month window and an instituted IPR at risk of termination due to a petition that may settle out of the parallel litigation.

At a minimum a petitioner seeking joinder must identify and justify all differences over the existing IPR, while also presenting a schedule and discovery plan that does not extend the schedule or increase the discovery burden of the existing parties. However, even if all of these guidelines are followed, the question of whether a party can join its earlier-filed IPR outside the 12-month window is still unresolved.

Reprinted with permission from the August 12, 2016 edition of the “Corporate Counsel”© 2016 ALM Media Properties, LLC. All rights reserved. Further duplication without permission is prohibited. – 877-257-3382 -