In an ANDA litigation, the District of Delaware recently denied the defendants’ motion to compel the production of correspondence between the plaintiffs’ testifying expert and a third-party analyst who had performed experiments and provided data used by the testifying expert. The court found that the scope of material sought by the motion was overbroad and disproportionate to the needs of the case.
As part of the plaintiffs’ infringement case, the plaintiffs’ expert engaged a third-party analyst to perform solid-state nuclear magnetic resonance (ssNMR) tests. The expert then used the data from those tests as a “filter” in later ssNMR experiments to determine if the defendants’ proposed ANDA products contained any crystalline material claimed by the plaintiffs’ patent.
The defendants’ motion to compel sought the production of correspondence between the expert and analyst regarding all ssNMR testing in the case. The plaintiffs objected on two grounds: (1) the information sought was protected from discovery as attorney work product and (2) the defendants had not demonstrated a need for additional information beyond the filtering experiments already produced by the plaintiffs.
In deciding the motion, the court first noted that the defendants did not seek counsels’ communications but rather sought communications between the expert and the third-party analyst.
As to the scope of material sought by the motion, the court held that it was overbroad and not proportional to the needs of the case under Federal Rule of Civil Procedure 26(b)(1). First, the court explained that the defendants identified only the filtering experiments as the impetus for the motion but had not limited the scope of the requested production to communications about those experiments. The court further explained that the defendants had failed to show that any information was lacking from the expert report and the raw data files that were produced.
Finally, the court rejected the defendants’ argument that there was no harm in producing a broader set of communications even if it contained previously disclosed information. The court explained that the request was not narrowly tailored even though the defendants had had a “fulsome opportunity to explore any gaps” after expert reports were served. Furthermore, the court found it “telling” that the defendants had rejected the plaintiffs’ offer to produce a privilege log, which would be the “first step” in narrowly targeting the communications at issue. The court explained that by rejecting the offer, the defendants showed that they were not interested in just facts, data, or assumptions but instead also sought to obtain materials that might include counsel’s advice, mental impressions, and strategies. The court determined that the defendants had not shown a substantial need for the additional materials or that the production would be proportional to the needs of the case.
(In the same order, the court also rejected the plaintiffs’ motion to strike portions of the defendants’ expert reports and related deposition testimony, which we discuss in a companion post.)
Practice Tip:
When seeking discovery of expert-related communications, parties should ensure that the scope of the request is tightly aligned with the justification offered and be prepared to identify what information is missing from existing expert disclosures. Broad requests untethered from a concrete showing of need—particularly where a privilege log is refused—risk denial on proportionality grounds.
Harmony Biosciences, LLC v. Lupin Ltd., Civil Action No. 23-1286-JLH-SRF (D. Del. Dec. 12, 2025)
