Key Points

• In multi-party Hatch-Waxman litigation, coordination does not excuse each party's individual obligation to conduct a diligent prior art search before the contention deadline.
• ANDA defendants in consolidated cases in the DNJ should treat invalidity contentions as final and conduct exhaustive prior art searches before the deadline regardless of coordination efforts because alignment and streamlining arguments will not substitute for diligence.
• Court denied generic-drug defendants leave to amend invalidity contentions to adopt a co-defendant's prior art theories.

Crafting a Discovery Confidentiality Order

A recent ANDA litigation decision from the District of New Jersey reinforces the need to develop invalidity theories early on under the Local Patent Rules and underscores the added logistical complexity that often accompanies cases with multiple defendant groups.

In In re Viloxazine, a group of generic-drug defendants asked to amend their invalidity contentions to adopt additional invalidity theories served by co-defendant Zydus in consolidated Hatch-Waxman litigation involving Qelbree®, an ADHD treatment produced by Supernus Pharmaceuticals.

U.S. Magistrate Judge Michael A. Hammer rejected the request, finding it ran afoul of the Local Patent Rules’ strict requirement that parties’ contentions be disclosed early, which is designed to require parties to crystallize positions near the outset of the case and enable full and timely discovery.

Multiple Defendants and Due Dates

In 2025, Supernus filed suit against six defendant groups (the “non-Zydus Defendants”) alleging infringement of six patents-in-suit, which included both formulation and method of treatment patents. Supernus filed suit against Zydus on June 26, 2025 but only as to the formulation patents. The Court entered a consolidation and scheduling order that required Defendants to serve any invalidity contentions by March 10, 2026.

Because Zydus had not yet been sued regarding the method of treatment patents, the non-Zydus Defendants worked on and jointly served contentions for those patents without Zydus. Shortly thereafter, Supernus filed a new suit against Zydus for infringement of the method of treatment patents, which suit was consolidated into the main consolidated action.

Zydus served invalidity contentions regarding the method of treatment patents on May 6, 2026. The Zydus invalidity contentions largely overlapped with the earlier-served invalidity contentions of the non-Zydus Defendants, but also asserted additional theories.

The non-Zydus Defendants then sought Supernus’s consent to amend their invalidity contentions to include these additional theories. Supernus refused, leading to the motion before the Court.

Lack of Diligence

In his decision, Magistrate Judge Michael A. Hammer began with Local Patent Rule 3.7, which says contentions may be amended “only by order of the Court upon a timely application and showing of good cause.” He found the non-Zydus defendants failed to establish good cause to amend because they did not show diligence in seeking leave.

The Court emphasized they “neither explain their failure or inability to discover the prior-art references, nor produce evidence of reasonable measures taken to find the prior art references that Zydus subsequently found and included in its contentions.” The Court also rejected the non-Zydus Defendants’ coordination-based argument, explaining that the usefulness of coordinated contentions did not excuse each defendant’s “fundamental obligation to conduct a diligent search for prior art and to formulate its invalidity contentions in a timely manner.”

In addition, the Court found this argument actually highlighted that Zydus was able to discover the prior art references and timely include them with its own invalidity contentions. The Court noted this case was dissimilar from circumstances in which courts had permitted amendments, such as the discovery of new information or a case of mistake.

Takeaways

In a prior alert, we noted that establishing good cause for an amendment to contentions under Local Patent Rule 3.7 is a high bar, and this decision illuminates that with several practical lessons about complying with DNJ rules:

• Where a proposed amendment to invalidity contentions is based on additional prior art or indefiniteness theories based on the claim language of the patent, the party seeking amendment should be prepared to explain why the information that forms the basis of the amendment was not discovered earlier.
• Courts may not allow such an amendment to avoid the presentation of different invalidity theories involving different experts.
• In contrast to other venues that allow for more flexibility through, e.g., preliminary and then final contentions, patent litigants in the DNJ should anticipate robust investigation and be prepared for disclosure of infringement and invalidity contentions in the early steps of litigation.

Paul W. Kalish and Jonathan J. Madara are members of the IP Litigation team in Fox Rothschild’s Princeton, NJ office and write about patent litigation decisions in the District of New Jersey. Contact Paul at pkalish@foxrothschild.com or 609.895.6751 and Jonathan at jmadara@foxrothschild.com or 609.844.7428.

This information is intended to inform firm clients and friends about legal developments, including the decisions of courts and administrative bodies. Nothing in this alert should be construed as legal advice or a legal opinion. Readers should not act upon the information contained in this alert without seeking the advice of legal counsel. Views expressed are those of the authors and not necessarily this law firm or its clients.