Key Points

• A DNJ court granted leave to amend infringement contentions under Local Patent Rule 3.7, finding good cause to add a doctrine of equivalents theory in this Hatch-Waxman litigation based on post-contention discovery production.
• The Court applied the good cause standard for amending patent contentions and credited Incyte's development of a DOE theory from late-produced discovery relating to Apotex's phosphate salt patents.
• The Court found no undue prejudice where amendment came before expert reports and no trial date had been set; the Magistrate Judge’s Order was affirmed on appeal, reinforcing DNJ patent rules flexibility.

New Jersey's Local Patent Rules generally demand early commitment, requiring parties to lock in their infringement theories while discovery is still unfolding and then live with the consequences. But a recent bench ruling from U.S. Magistrate Judge Matthew J. Skahill reiterates that DNJ judges may recognize diligence in the face of the Local Rules’ rigidity, even when the evidence supporting amendment is admittedly "thin."

Early Disclosure But No Straitjacket

As the Court noted in Amgen Inc. v. Kashiv Biosciences LLC, the DNJ’s Local Patent Rules “are designed to require the parties to crystallize their theories of the case early in the litigation and to adhere to those theories once they have been disclosed.”

But the rules do provide some flexibility. As we discussed in a prior alert, the Local Patent Rules require relatively early service of infringement and invalidity contentions as compared to other districts. Importantly, Local Patent Rule 3.7 provides that amendment of a party’s contentions may be made “only by order of the Court upon a timely application and showing of good cause.”

In his bench ruling in Incyte Corp. et al. v. Apotex Inc., Magistrate Judge Skahill explained that he was granting a motion for leave to amend infringement contentions because “Rule 3.7 is not a straitjacket into which litigants are locked from the moment the contentions are served.”

Background

In the case, a consolidated Hatch-Waxman action, plaintiffs Incyte Corp. and Incyte Holdings Corp. (collectively, Incyte), served initial infringement contentions on September 22, 2025. These initial infringement contentions focused solely on literal infringement and did not assert an infringement theory under the doctrine of equivalents (DOE).

According to Incyte, Apotex subsequently provided “key information about its NDA Product,” ultimately revealing “additional critical information during depositions in December,” after fact discovery had closed. Following a meet and confer between the parties, Incyte moved for leave to amend its infringement contentions to assert a DOE theory on December 19, 2025, approximately three months after the service of its initial infringement contentions. Incyte primarily sought to amend its contentions as a result of “discovery that Apotex delayed or withheld.”

Apotex opposed Incyte’s motion, arguing that Incyte had not demonstrated the required diligence in moving to amend. More specifically, Apotex argued that “Incyte had enough information to make the allegations it seeks to add when it served its initial contentions, including Apotex’s new drug application, drug master file, and other internal documents relating to the accused product.”

Incyte “wants a do-over,” Apotex argued, “to explain for the first time why the same samples and documents it used to assert literal infringement now support an entirely new DOE argument.” Apotex further argued that any discovery it had produced after the service of the initial infringement contentions was cumulative, and that permitting the new DOE theory to be introduced now would require the reopening of fact discovery.

A Showing of Three Things

The Court granted Incyte’s motion for leave to amend its infringement contentions to include the DOE theory at a status conference with the parties. The Court began with an analysis of the requirements of Local Patent Rule 3.7, which allows for amendment upon a showing of three things: “that the application is timely, that there's good cause for the amendment, and that the adverse party will not suffer undue prejudice if leave to amend is granted.”

Several factors informed the good cause analysis, the Court noted, “including the reasons for the delay and whether the moving party has been diligent, prejudice to the non-moving party, and the impact of a delay on judicial proceedings.”

But the Court emphasized that “diligence is the dominant consideration in determining whether good cause exists under Rule 3.7.”

The Court determined that Incyte was diligent in moving for leave to amend its contentions. The Court noted that “[r]ather than use cumulative discovery to assert a new theory after its literal infringement theories appeared inadequate, Incyte essentially asserts that it continually worked to develop a DOE theory from the information it had at its disposal, which was bolstered by discovery production made by Apotex after its initial contentions were served.” Although the evidence Incyte pointed to “may be thin,” the Court found that “it likely weighs slightly in favor of granting the motion.”

The Court next found Incyte’s motion for leave to amend to be timely, finding “[d]iscovery was received from Apotex, and over the next three months, this application was thereafter filed.” Accordingly, the Court found good cause for Incyte’s motion for leave to amend.

The Court next turned to an analysis of potential undue prejudice to Apotex, as required after finding good cause to grant leave to amend. The Court considered that “expert reports have not been exchanged, a trial date has not been set, and additional expenses in amending responses to contentions does not constitute undue prejudice.” Additionally, the Court held that Apotex would not be “genuinely surprised or harmed by the amendment.”

The Court considered Apotex’s argument that Incyte should have brought the DOE theory in its initial infringement contentions based on “the documents [Apotex] produced and the patent application it submitted.” However, based on this argument, the Court held that Apotex would not now “suffer genuine surprise from amendment because this information is not new to Apotex.”

Apotex appealed Magistrate Judge Skahill’s order to U.S. District Judge Christine P. O’Hearn. After briefing, Judge O’Hearn denied the appeal, affirming Judge Skahill’s ruling.

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.