The IPR estoppel rule puts certain restrictions on a petitioner's ability to challenge a patent.

Current IPR Estoppel Rules

The purpose of the inter partes (IPR) estoppel rule is to prevent frivolous challenges to patents before the United States Patent and Trademark Office's (USPTO) Patent Trial and Appeal Board (PTAB). Under this rule, challenges to patents cannot be based on grounds that could have been raised during an IPR.

Typically, common law estoppel rules can be different depending on the jurisdiction, and in most cases, will be left up to the discretion of the court. Under 35 U.S.C. Section 315(e), however, estoppel is mandatory. Generally, when an IPR is requested, the petitioner will have a variety of grounds for contesting the patent.

The PTAB will accept or decline requests for an inter partes review on an individual basis and will have several options for responding to the request:

  • Declining to institute the IPR.
  • Allowing the IPR to proceed on all grounds.
  • Accepting the IPR on certain grounds.

There will be two stages to an IPR: discovery and hearing. After these stages have been completed, a final decision will be issued by the PTAB. Estoppel rules will apply both to proceedings of the PTAB and district courts. Multiple grounds can result in an IPR estoppel. Recently, the PTAB and the courts have developed different understandings of the estoppel rules in Section 315(e), including the scope of these rules and how they can be applied.

Grounds for IPR Estoppel

A variety of court cases are related to whether or not estoppel applies to an inter partes review. In one case, for instance, the court ruled that estoppel rules will not apply until the IPR has actually been instituted by the PTAB. This is because non-instituted grounds could not have been raised because the IPR never actually took place.

In another case, it was decided that simply because an IPR contention was denied, it doesn't mean that the contention is invalid. The court in this case also reasoned that grounds that have not been instituted do not mean that estoppel is applicable.

The Changing Scope of Estoppel

One of the most important pieces of legislation related to estoppel is the America Invents Act of 2011. This act changed the rules for challenging a patent that had already been granted. Basically, the AIA states that a person challenging a patent by requesting an IPR cannot assert that the patent is invalid based on grounds that would have been reasonably raised during the IPR.

While this may seem fairly straightforward, district courts have had a very difficult time determining the actual scope of the IPR estoppel rules. The two factors that have complicated this issue are grounds that the USPTO did not institute but were included in the petition, and grounds that should have been known but were not included in the petition.

One recent case in the United States District Court in Massachusetts went against traditional understanding by not applying estoppel rules for either of these grounds. The court ruled in this manner because it was reluctant to broaden the current estoppel rules. District courts have increasingly come to the opinion that estoppel does not apply to grounds that were included in the petition but were not instituted by the PTAB. Estoppel does apply, however, to grounds that the petitioner should have raised but failed to do so.

This decision made by the Massachusetts District Court represents a big change in how the scope of estoppel rules are viewed. This new view restricts estoppel from being applied to grounds that were not included in an inter partes review.

A pending Supreme Court decision may have a big impact on IPR estoppel, although the question being raised is different than the previously mentioned district court cases. The question in front of the court is whether the PTO is required to institute an IPR on all the challenged claims of a patent or if it has the ability to pick and choose which claims will be reviewed. Depending on the final ruling of the court, the scope of IPR estoppel rules, as well as how these reviews take place, may be greatly altered.

If you need help with determining IPR estoppel, you can post your legal needs on UpCounsel's marketplace. UpCounsel accepts only the top 5 percent of lawyers to its site. Lawyers on UpCounsel come from law schools such as Harvard Law and Yale Law and average 14 years of legal experience, including work with or on behalf of companies like Google, Menlo Ventures, and Airbnb.