Unreported / Non-Citable
Background
Collision Communications filed suit against Samsung on December 12, 2023, alleging infringement of six United States patents. Samsung served its invalidity contentions on June 3, 2024. Fact discovery closed on April 7, 2025, followed by expert discovery closing on May 30, 2025. On May 2, 2025—after both discovery phases had concluded—Samsung moved for leave to amend its invalidity contentions to add a new prior art system called the Vertical-Bell Laboratories Layered Space-Time (“V-BLAST”) system and to take up to two additional third-party depositions.
Samsung argued it first discovered V-BLAST on March 25, 2025, at the deposition of Dr. Brandon Hombs, an inventor of one of Collision’s asserted patents. Samsung claimed it thereafter diligently pursued additional discovery and included V-BLAST in its invalidity expert report. Collision opposed the amendment, arguing Samsung lacked diligence and that V-BLAST was not newly discovered but rather was discussed in references Samsung had already identified in its initial contentions and IPR filings.
The Court’s Holding
The court applied the four-factor good-cause test governing amendments to invalidity contentions: (1) explanation for failure to meet the deadline; (2) importance of the excluded matter; (3) potential prejudice from allowing the amendment; and (4) availability of continuance to cure prejudice. The burden to demonstrate good cause rested with Samsung.
On diligence, the court found Samsung’s showing inadequate. While Samsung argued it only discovered V-BLAST through the Hombs deposition, the court noted that V-BLAST was discussed in multiple prior art references Samsung had already identified in its initial invalidity contentions and IPR filings nine months earlier. The court rejected Samsung’s contention that it could not have discovered V-BLAST during its initial investigation of those references or in its prior art search. The nearly nine-month gap between serving initial contentions and the alleged “discovery” of V-BLAST remained unexplained and suggested Samsung lacked diligence.
On importance, Samsung only offered conclusory statements that V-BLAST invalidated the asserted patents and would help the jury visualize the prior art. Samsung made no attempt to demonstrate that V-BLAST was not cumulative to the twelve or more other prior art references it had already charted against each asserted patent. The court also rejected Samsung’s argument that V-BLAST was relevant to a non-infringement defense, noting that practicing prior art is not a valid defense to infringement under Federal Circuit precedent.
On prejudice, the court found Collision would suffer clear prejudice. The case had reached an advanced stage with both fact and expert discovery closed, dispositive motion briefing underway, and trial scheduled within three months. Allowing the amendment would require reopening both fact and expert discovery. Neither party sought a continuance, and the court deemed one inappropriate given the trial proximity.
Key Takeaways
- Parties must demonstrate diligence in meeting invalidity contention deadlines; discovering prior art mentioned in existing references does not excuse delay in amendment
- Conclusory assertions of importance are insufficient to satisfy the good-cause standard; parties must demonstrate how newly proposed prior art is not cumulative to existing contentions
- Courts will deny late-stage amendments to invalidity theories when discovery has closed and trial is imminent, even if opposing counsel has notice through expert reports
- Practicing prior art is not a cognizable non-infringement defense; amendments premised on this theory lack legal merit
Why It Matters
This decision reinforces the Federal Circuit’s well-established requirement that defendants demonstrate diligence when seeking to amend invalidity contentions outside express procedural exceptions. The court’s holding prevents gamesmanship whereby a party could theoretically sit on prior art references, cite them for other purposes, and then opportunistically add them as separate invalidity theories late in litigation. By requiring parties to conduct adequate prior art searches at the outset and to explain why newly identified systems should have been discovered earlier, courts maintain the integrity of discovery schedules and prevent trial disruption.
The decision also clarifies that notice of a theory through an expert report, standing alone, does not cure procedural failure to include that theory in timely invalidity contentions. This protects plaintiffs from having to engage in costly and disruptive reopening of discovery based on theories not properly pleaded within deadlines, and ensures that trial dates remain meaningful constraint on litigation scope.