
Five copyright holders sued Databricks and Mosaic ML, claiming their copyrighted works were used to train artificial intelligence systems without permission. Plaintiffs originally alleged that Mosaic ML directly infringed their works by training its MPT large language models on datasets that included their works. Plaintiffs also accused Databricks, Mosaic ML’s parent company, of vicarious liability for that conduct.
After Databricks released a new set of AI models called DBRX, plaintiffs moved to amend the complaint. Plaintiffs asked the court to allow a new claim of direct copyright infringement against Databricks for allegedly using the same protected works to train DBRX. Plaintiffs also sought to update the list of copyrighted works allegedly copied. Defendants opposed the request, arguing that the amendment came too late and would unfairly change the case.
Timing
The court acknowledged that plaintiffs waited more than a year after DBRX was released before requesting to amend the complaint. That delay was significant, and plaintiffs did not provide a strong explanation. However, the court noted that discovery was still open, and key deadlines had not yet passed. Because the case was still active, the court said the delay alone was not enough to deny the motion.
Intent
Defendants claimed plaintiffs acted in bad faith by dragging out the case and making vague statements in court filings. But the court saw no signs of deliberate delay or dishonesty. Instead, it found that plaintiffs’ motion to amend reflected an effort to match the complaint with new information obtained through discovery.
Prejudice
Defendants argued that allowing new claims about DBRX would cause unfair prejudice by drastically changing the case. The court disagreed. It found that the parties were already engaged in discovery related to DBRX and that any added burden would be limited. Since the DBRX and MPT models might rely on overlapping data, the new claims would not require a completely new approach to the case.
Futility
Defendants also said the new claims were too vague and would not survive a challenge. But the court said such issues should be dealt with after the complaint is amended. Unless the new claims are clearly invalid, courts usually allow amendments and address legal sufficiency later in the process.
So the court granted plaintiffs’ motion to amend. The lawsuit will now include direct copyright infringement claims against Databricks based on its newer DBRX models, along with an updated list of works that plaintiffs claims were copied.
In re Mosaic LLM Litigation, 2025 WL 1755650 (N.D. California, June 25, 2025)
