Lack of Diligence in Deposing Key Inventor Precludes Amending Answer to Add Inequitable Conduct Defense

January 17, 2024

Reading Time : 2 min

The Central District of California denied a defendant’s motion for leave to amend to allege inequitable conduct due to the defendant’s delay in deposing a key inventor until the end of fact discovery. The district court held that the defendant neither exercised diligence nor established good cause based on the inventor’s deposition to warrant amending its answer.

In a patent infringement lawsuit over printer and printing method patents, Defendant deposed the first named inventor of the patents two weeks before the end of fact discovery. The inventor testified that he had used information about a printhead manufactured by a third party in the design of the claimed inventions. Patentee then produced related documents after the deposition and two days before the close of fact discovery. Defendant argued that Patentee intentionally withheld this critical information about the printhead until the end of discovery, depriving Defendant of the ability to allege inequitable conduct sooner. Defendant filed a motion to amend its answer to assert inequitable conduct following the Patentee’s production—eight months after the deadline to amend pleadings.

Patentee argued in opposition to the motion that it had produced relevant documents about the claimed invention’s functionality earlier in the case, that the information that formed the basis for Defendant’s motion was cumulative of prior discovery and that the information was not material to patentability. Patentee further argued that Defendant was at fault for delaying the deposition at which it learned of the printhead information until two weeks before the end of fact discovery and four months before trial. Thus, Defendant was not diligent.

The court agreed with Patentee, concluding that Defendant was not diligent and thus failed to show good cause to modify the court’s scheduling order pursuant to Rule 16(b)(4) long after the deadline to amend pleadings. Although Defendant noticed the deposition in March and the parties had a dispute over its location, the district court faulted Defendant for waiting several months to bring the location dispute to its attention. The court also found that Defendant failed to identify any testimony that supported a “sudden revelation of inequitable conduct.” The court also held that Defendant failed to meet the requirements to amend its pleading under Rule 15 because, inter alia, it failed to alleged facts sufficient to support a reasonable inference of specific intent.

Practice Tip: When choosing the timing of key depositions, parties must consider the potential consequences of discovering relevant information late in the discovery period. Courts may be reluctant to permit amendments or additional discovery when it is likely to be time-consuming, costly or delay resolution of the case even if that discovery was requested, but not provided earlier in the case if the requesting party did not seek the court’s assistance in ensuring that such discovery was provided earlier.

MGI Digital Technology SA v. Duplo USA Corporation, 8-22-cv-00979 (CDCA Oct. 17, 2023).

Share This Insight

Previous Entries

IP Newsflash

August 11, 2025

In considering a motion to dismiss infringement claims for two related patents, the District of Massachusetts recently held that pre-suit knowledge of a “parent” patent, without more, is insufficient to establish pre-suit knowledge of the “child” patent for purposes of indirect and willful infringement.

...

Read More

IP Newsflash

August 8, 2025

Following a jury verdict finding trade secret misappropriation, the District Court for the District of Massachusetts granted-in-part a plaintiff’s motion for a permanent injunction to prohibit defendants from using plaintiff’s trade secrets. The district court further required defendants to reassign to plaintiff patents and patent applications that disclosed or were derived from plaintiff’s trade secrets as part of its equitable relief.

...

Read More

IP Newsflash

August 6, 2025

In ruling on a recent motion to strike, a judge in the Eastern District of Texas permitted a damages expert to rely on a damages theory based on defendant’s “avoided costs,” holding that this theory did not run afoul of the “entire market value rule.”

...

Read More

IP Newsflash

August 5, 2025

The Federal Circuit recently vacated a decision by the Patent Trial and Appeal Board after concluding that the board’s analysis of licensing evidence offered as a secondary consideration of nonobviousness constituted legal error and was not supported by substantial evidence. According to the court, the board applied a more exacting and improperly heightened nexus standard than is required by law for license evidence.

...

Read More

IP Newsflash

August 5, 2025

A Northern District of California judge recently granted a motion to reconsider his summary judgment ruling that defendant was barred from raising certain “device art” due to IPR estoppel under 35 U.S.C. § 315(e)(2). In the original ruling, the judge adopted the broader rule that IPR estoppel applies to device art that is “materially identical” to patents or printed publications that petitioners raised, or could have raised, in an IPR. Following that ruling, however, the Federal Circuit issued its Ingenico decision adopting the narrower view that IPR estoppel applies only to “grounds” based on patents and printed publications and not to device-based grounds. Citing Ingenico as a “change of law,” defendant moved for reconsideration of the court’s ruling, and the court granted the motion.

...

Read More

IP Newsflash

August 5, 2025

In a recent decision designated as Informative, the USPTO Director determined that the Patent Trial and Appeal Board abused its discretion by instituting two inter partes review proceedings challenging the same patent, based on petitions advancing different constructions of the same claim term. The Director expressed concerns that permitting multiple petitions based on alternative claim constructions effectively circumvents word count limitations, strains board resources, and undermines procedural efficiency.

...

Read More

IP Newsflash

July 25, 2025

Earlier this year, the Federal Circuit’s decision in Qualcomm Inc. v. Apple Inc. (Qualcomm II) raised questions about the extent to which petitioners can rely on applicant admitted prior art (“AAPA”) in inter partes review proceedings.  The Federal Circuit’s recent decision in Shockwave Medical, Inc. v. Cardiovascular Sys., Inc. largely cabins the Qualcomm II decision to its particular facts and makes clear that AAPA can be used as evidence of background knowledge as part of an obviousness argument.

...

Read More

IP Newsflash

July 11, 2025

The Federal Circuit recently reversed a PTAB determination on remand that a patent was obvious over applicant admitted prior art (“AAPA”) in combination with prior art patents, holding that expressly designating AAPA as a “basis” for a ground is improper under 35 U.S.C. § 311(b). In doing so, the Court rejected the PTAB’s “blanket rule” that “AAPA used in combination with prior art patents or printed publications under § 311(b) is ipso facto not the basis or part of the basis of a ground.” Ultimately, while the case clarifies that expressly listing AAPA in an IPR ground is improper, the precise line between proper and improper uses of AAPA in other instances remains unclear.

...

Read More

© 2025 Akin Gump Strauss Hauer & Feld LLP. All rights reserved. Attorney advertising. This document is distributed for informational use only; it does not constitute legal advice and should not be used as such. Prior results do not guarantee a similar outcome. Akin is the practicing name of Akin Gump LLP, a New York limited liability partnership authorized and regulated by the Solicitors Regulation Authority under number 267321. A list of the partners is available for inspection at Eighth Floor, Ten Bishops Square, London E1 6EG. For more information about Akin Gump LLP, Akin Gump Strauss Hauer & Feld LLP and other associated entities under which the Akin Gump network operates worldwide, please see our Legal Notices page.