Patent disputes in the United States often unfold on two parallel tracks: the federal district courts and the Patent Trial and Appeal Board (PTAB). While these forums serve different purposes, they frequently overlap, especially when questions of patent validity arise. This article explains how these two systems interact and the strategic issues that emerge when litigating in both arenas.

PTAB Trials

PTAB trials, such as inter partes reviews (IPRs) and post-grant reviews (PGRs), were created to provide a faster, more cost-effective way to challenge patent validity. As Roshan Mansinghani of Unified Patents notes, between 80–90% of patents challenged in PTAB trials are also involved in co-pending litigation, making the PTAB an important factor in most significant patent disputes.

Compared with district court litigation, PTAB proceedings move faster, focus solely on validity, rely heavily on the written record, and use a lower evidentiary standard, i.e., ‘preponderance of the evidence’ rather than ‘clear and convincing evidence.’

District courts frequently stay litigation when a PTAB petition is filed, but approaches vary widely by jurisdiction. Courts typically look at (1) the status of the litigation, (2) whether PTAB review will simplify the issues, and (3) whether either party will suffer unfair prejudice.

For example, courts in California are more likely to stay litigation early, even before PTAB institution. Courts in Texas, by contrast, often deny stays unless every asserted claim is under PTAB review and the PTAB is likely to finish before the district court’s trial date.

The Evolving PTAB Trial Landscape

Recent developments have shifted institution decisions from panels of administrative judges to direct review by the United States Patent and Trademark Office (USPTO) Director. Many of these decisions now issue as short ‘summary notices,’ with little indication whether institution was denied based on the merits or discretionary criteria. The USPTO has also proposed additional regulations around IPRs that could effectively make this type of patent challenge a non-option for challengers.

Due to the currently evolving landscape, it is critical that petitioners and their counsel stay abreast of changes in regulation as they coordinate strategy.

Key Differences Between PTAB Trials and the District Courts

Claim Construction

Historically, PTAB claim construction differed from that used in district courts, but today both use the ‘Phillips standard.’ This alignment has reduced conflict between forums, although the PTAB still evaluates validity with no presumption of validity.

When a district court issues a claim-construction order, the PTAB must consider it and, if deviating, must explain its reasoning in detail. This heightened deference encourages consistency across forums. However, PTAB judges still may refine constructions based on the issues presented in the administrative record.

These dynamics produce strategic considerations. For example, arguments made early in a PTAB petition may inadvertently narrow a party’s later district-court positions, or vice versa. For these reasons, lawyers must consider not just how arguments play before the PTAB but how they affect the broader litigation landscape, advises Patrick Richards of Much Shelist, P.C.

Discovery

In district court, discovery is generally broad, while PTAB discovery is narrow and usually limited to cross-examination of declarants or evidence already referenced in filings.

PTAB proceedings provide four categories of discovery:

• mandatory disclosures,
• routine discovery,
• additional discovery, and
• live testimony (rarely).

Additional discovery requires permission and is granted sparingly under the Garmin Factors, which require that requests be narrowly tailored, readily understandable, and not burdensome. Broad document requests that resemble traditional litigation are usually denied.

Because PTAB discovery is limited, parties must assemble the bulk of their evidentiary record, especially expert declarations, at the outset. This front-loaded structure can sometimes disadvantage patent owners, who may need more factual development.

Estoppel: The Most Consequential Effect of PTAB Trials

Despite the differences between the two venues, the arguments made in one forum can create estoppel in the other, and so litigators must therefore coordinate positions across both systems.

Estoppel attaches once the PTAB issues a final written decision, preventing petitioners from raising in district court any invalidity grounds they raised, or reasonably could have raised, before the PTAB.

Some litigants try to avoid estoppel by discovering new prior art later, but courts often require detailed proof of a diligent search. More recently, discretionary denial practices have effectively pulled estoppel forward: some petitioners now stipulate that estoppel-like restrictions apply upon institution, not after final written decision.

Settlement Dynamics

PTAB petitions often create settlement leverage. A strong petition can narrow claims, force amendments, or put the patent at risk of cancellation. Even partial PTAB success. such as invalidating one of several asserted patents, can reshape district-court strategy and encourage compromise.

The PTAB may terminate a proceeding if both parties jointly request it, but only if the case is not already too far developed. If the Board proceeds to a final written decision, estoppel applies, but if it terminates early due to settlement, estoppel does not.

Coordinating a Two-Front Patent Fight

Litigants navigating both venues must approach them as two parts of a unified strategy. Early filing, consistent claim-construction positions, cautious discovery requests, and awareness of estoppel implications are critical. In the end, understanding the strategic interplay between these forums helps companies protect their innovations, manage litigation risk, and make better business decisions.

To learn more about this topic, view Interplay With District Court Litigation. The quoted remarks referenced in this article were made either during this webinar or shortly thereafter during post-webinar interviews with the panelists. Readers may also be interested in reading other articles about intellectual property.

This article was originally published here.

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