Intellectual Property Law Blog 

For parties facing allegations of patent infringement, there are several ways to challenge the validity of patents outside of the courtroom. These alternative pathways are often preferred by accused infringers because they are often significantly less expensive and potentially speedier than federal district court litigation. Accused infringers can use U.S. Patent and Trademark Office (USPTO) procedures by filing either an inter partes review (IPR) or an ex parte reexamination (EPR). Although both allow the accused infringer to use the USPTO as a forum to challenge patent validity, the mechanisms differ substantially in adversarial posture, timing, cost, estoppel effect, and strategic implications when parallel litigation is in play.

The strategic use cases for each of these pathways continue to develop with each administration (and hence USPTO Director) as policies change, patent owner and patent challenger strategies adapt, and USPTO policies adjust in response to these adaptations.

Below is a breakdown of key similarities, differences, and strategic use cases.

1. Party Participation

• IPR is an adversarial proceeding before the PTAB. The Petitioner participates throughout the proceeding with briefing, expert declarations, discovery, and potential oral hearing.
• EPR is non-adversarial after initiation. A Requester files the Request for Reexamination but does not further participate in the reexamination proceedings after the initial institution decision.

Practical Implication: EPRs are significantly less expensive compared to IPRs because there is no discovery in an EPR and no opportunity for the petitioner to submit arguments after the initial Request is filed. But, because the patent challenger is not permitted to make arguments after the initial Request in an EPR, there is some inherent risk for the challenger. So, the patent challenger must determine whether the ability to respond to patentee arguments justifies the significantly higher cost.

2. Estoppel

• IPR Petitioners are estopped from later asserting in litigation “any ground that was raised or reasonably could have been raised” in the IPR. 35 U.S.C. § 315(e).
• EPR has no statutory estoppel for requesters, so if the Requestor’s argument in an EPR is not successful, the Requestor can still make that same invalidity argument in litigation and potentially get another bite at the apple.

Practical Implication: A patent challenger that chooses to file a Petition for IPR rather than a Request for EPR should develop a comprehensive prior-art strategy at the outset since the challenger will be estopped from making the same arguments during litigation. A patent challenger that chooses to file a request for EPR can use the procedure as a lower-risk tactical probe or parallel pressure point, since the challenger will be allowed to make the same invalidity arguments in district court.

3. Timing

• The USPTO determines whether institution is appropriate much more quickly in an EPR proceeding (~3 months after petition) than in an IPR proceeding (closer to 6 months after petition).
• After the initial institution decision, an IPR must be complete within 12 months, but an EPR can last much longer, depending upon the technology involved (art unit).

Practical Implication: A quicker institution decision is advantageous to many accused infringers that have been sued in federal district courts because courts are more likely to grant a stay of district court litigation (pending decision by the USPTO) when there is an institution decision at the USPTO earlier in the litigation. Timing is key. Thus, because a challenger can likely get an institution decision in an EPR quicker than in an IPR, it may be advantageous for a patent challenger to file a request for EPR rather than a petition for IPR if there is an already-filed federal district court litigation. If there is no litigation filed or no chance for a stay of the litigation (because it is too far progressed), then a patent challenger may choose to file a petition for IPR rather than a request for EPR for a more predictable (and potentially speedier) timeline to completion.

Conclusion: No One-Size-Fits-All Tool

A patent challenger’s decision to file a petition for IPR versus a request for EPR often turns on three threshold questions:

1. Is there concurrent litigation—and, if so, how far along is it?
2. Can you live with estoppel?
3. What is the budget relative to the value of invalidating the patent?

A well-structured defense strategy may even involve both IPR and EPRs for the same patents. However, the USPTO has recently taken note of these patent challenger strategies and, in an effort to prevent serial challenges to the same patents, denied requests for EPRs based on prior IPR discretionary (non-substantive) denials. See U.S. Patent Application No. 90/015,982. Although patent challengers are not estopped from making the same arguments in an EPR that they already made in an IPR, the USPTO can deny institution of an EPR based upon an earlier-filed IPR under Section 325(d), which states that review requests can be denied if the same arguments were previously presented to the office.

Porter Hedges attorneys have successfully represented clients in both IPR and EPR proceedings and have obtained stays of district court litigation pending USPTO review, helping clients manage costs while pursuing strategic patent validity challenges.