In Re Mosaic LLM Litigation

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United States District Court
Northern District of California
UNITED STATES DISTRICT COURT
NORTHERN DISTRICT OF CALIFORNIA
STEWART ONAN, et al.,
Plaintiffs,
v.
DATABRICKS, INC., et al.,
Defendants.
Case No. 24-cv-01451-CRB (LJC)
ORDER REGARDING DISCOVERY
DISPUTE AT ECF NO. 248
Re: ECF Nos. 246, 248
The parties disagree over (1) whether Defendants must answer Plaintiffs’ Interrogatory
Nos. 42-50, (2) whether Defendants must produce licensing agreements for text data and related
communications, and (3) whether Patrick Wendell may be designated as a document custodian.
ECF Nos. 247-3, 248.1 The close of fact discovery, originally set for November 21, 2025, was
continued to January 5, 2026. ECF No. 238. Having considered the record in this case, the
parties’ arguments, and the relevant legal authority, the undersigned rules as follows: Defendants
shall answer Plaintiffs’ Interrogatory Nos. 42-50. Defendants shall produce licensing agreements
for text data (but do not need to produce related communications). Defendants are not required to
conduct a search of Patrick Wendell’s custodial file. The joint administrative motion at ECF No.
246 is granted.
I. INTERROGATORY NOS. 42-50
Federal Rule of Civil Procedure 33(a) provides that, “unless otherwise stipulated or
ordered by the court, a party may serve on any other party no more than 25 written
interrogatories.” The plain language of Rule 33(a) suggests that “each plaintiff may serve each
1 The parties filed a copy of their letter brief with redactions on the public docket at ECF No. 248.
The unredacted copy has been filed under seal at ECF No. 247-3.
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defendant with 25 interrogatories.” Trevino v. ACB Am., Inc., 232 F.R.D. 612, 614 (N.D. Cal.
2006). However, courts often read Rule 33(a) “to include some reasonable limit” on the number
of interrogatories that may be served in a multi-plaintiff action. Herroz v. CRST Van Expedited,
Inc., No. ED CV 15-507, 2015 WL 13914976, at *3 (C.D. Cal. Nov. 2, 2015) (explaining that
“[s]urely if twelve plaintiffs, all identically situated and acting in unison, brought a lawsuit, they
would not be permitted 300 interrogatories”). “District courts have applied the 25-interrogatory
limit as a ‘per side’ rule when the parties to an action are nominally separate,” that is, “when
represented by a single attorney, when there is a unity of action, or when there is a legal
relationship between the parties.” Fate Therapeutics, Inc. v. Shoreline Biosciences, Inc., No. 22-
cv-00676, 2023 WL 4142009, at *1 (S.D. Cal. June 22, 2023) (internal quotations omitted)
(collecting cases). “[T]he decision to consider multiple parties as one for the purposes of Rule
33(a) is within the discretion of the court.’” Herroz, 2015 WL 13914976, at *3 (quoting Rahman
v. Smith & Wollensky Rest. Grp., Inc., 2007 WL 1521117, at *8 (S.D.N.Y. May 24, 2007)).
There are five named Plaintiffs in this case: Stewart O’Nan, Abdi Nazemian, Brian Keene,
Rebecca Makkai, and Jason Reynolds. See ECF No. 131. They are represented by the same
counsel, are advancing the same claims, and, at least at this point in the litigation, are acting in
concert with one another. See, e.g., id.; ECF No. 196 (motion by all Plaintiffs to modify
scheduling order and for leave to file second amended complaint). Plaintiffs argue that under
Rule 33’s twenty-five-interrogatories-per-party limit, having served fifty interrogatories total is
warranted. See ECF No. 247-3 at 2-3. Defendants argue that Plaintiffs should be treated as one
party – and, collectively, be permitted to serve 25 interrogatories – because they are similarly
situated, acted in unison, and jointly served the same interrogatories. Id. at 4-5.
Given that Plaintiffs are represented by the same counsel and are jointly litigating this
action, Defendants’ argument is reasonable. See Fate Therapeutics, 2023 WL 4142009, at *1. It
is also somewhat besides the point. “Leave to serve additional interrogatories may be granted to
the extent consistent with Rule 26(b)(1) and (2).” Fed. R. Civ. P. 33(a). Given “the importance of
the issues at stake in the action, the amount in controversy, the parties’ relative access to relevant
information, the parties’ resources,” exceeding the twenty-five interrogatory limit is appropriate.
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Fed. R. Civ. P. 26(b)(1); see Herroz, 2015 WL 13914976, at *4 (“[P]laintiffs have served only 51
or so interrogatories, not 100. Given the complexity of the case, the court would grant plaintiffs
leave to serve more than 25 interrogatories in any event.”). Defendants are accordingly ordered to
answer Interrogatory Nos. 42-50.
II. THIRD-PARTY LICENSING AGREEMENTS
Plaintiffs’ Request for Production No. 3. requests “[a]ll agreements, licenses, partnerships, or
collaborations, and any Documents or Communications regarding potential agreements, licenses,
partnerships, or collaborations related to the acquisition and/or use of the Training Data.” ECF No. 207-1
at 10. Defendants objected to this request, but agreed to produce documents showing agreements “by
which Mosaic acquired and/or used data from the RedPajama – Books Dataset and Books3 Dataset to train
the [MPT] models identified in the Complaint.” Id. at 11. Plaintiffs now seek an order compelling
Defendants to produce licensing agreements they entered into with third parties to obtain curated training
data for LLM training. ECF No. 247-3 at 3. Plaintiffs point to the undersigned’s earlier Order, where she
found that nonparty Microsoft’s licensing agreements with publishers to obtain books for LLM training
were relevant. Defendants oppose Plaintiffs’ request, arguing that the agreements Plaintiffs seek “have no
connection to this litigation,” as they are not “related to the MPT models nor are they agreements for
[licensing] books.” ECF No. 247-3 at 5.
Defendants are correct that the instant request is different from Plaintiffs’ request for Microsoft’s
licensing agreements. There, the undersigned recognized that evidence that Microsoft had paid for what
Defendants allegedly stole was arguably relevant to Defendants’ anticipated fair use argument in that it
could show (1) the damage to Plaintiffs from Defendants’ alleged infringement and “unrestricted and
widespread conduct of the sort engaged in by” Defendants and (2) that Defendants could have obtained an
immense corpus of written work to train their LLMs through licensing with authors or publishers rather
than alleged infringement. ECF No. 152 at 8; Campbell v. Acuff-Rose Music, Inc., 510 U.S. 569, 590
(1994) (internal quotations omitted); see 17 USC § 107.
Key to the undersigned’s reasoning was that Microsoft’s licenses were with publishers for
permission to use books for LLM development. How much Microsoft was willing to pay for those books
may illustrate what Plaintiffs could have made from licensing their own books, but for the alleged
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infringement, and what Plaintiffs stand to lose.2 Similarly, the feasibility of technology companies
assembling “convenient, general-purpose librar[ies] of works” through licensing rather than copying could
undercut arguments that any alleged copying was necessary for technological advancement. Bartz, 787 F.
Supp. 3d at 1033; see, e.g. Kadrey v. Meta Platforms, Inc., 788 F. Supp. 3d 1026, 1050 (N.D. Cal. 2025)
(quoting Google LLC v. Oracle America, Inc., 593 U.S. 1, 3 (2021)) (discussing “the public benefits the
copying will likely produce”). In contrast, how much Defendants were willing to pay other technology
companies for curated datasets designed to fine-tune LLMs to perform specific tasks says relatively little
about whether—or how much—Defendants would have paid Plaintiffs for their written works or “the effect
of” the alleged infringement “upon the potential market for or value of the copyrighted work.” Campbell,
510 U.S. at 590 (quoting 17 U.S.C. § 170).
But this case may very well rise or fall on whether Defendants’ alleged use of Plaintiffs’ works was
fair. Fair use is a “flexible” concept, “the application of which requires judicial balancing, depending upon
relevant circumstances, including significant changes in technology.” Oracle, 593 U.S. at 19-20. Fair use
in the context of generative AI training is a novel area of law, and the undersigned is hesitant to unduly
limit the scope of discovery in a manner that could foreclose fair use arguments the parties may advance.
Judge Breyer may consider Defendants’ willingness and ability to pay for licensing training data—even
training data in a different form, acquired for a different express purpose—in evaluating whether
Defendants alleged use of Plaintiffs’ works was fair. In general non-privileged information “relevant to
any party’s claim or defense” may be discoverable. Fed. R. Civ. P. 26(b)(1). “‘[R]elevancy’ is construed
broadly.” Alves v. Riverside Cnty., 339 F.R.D. 556, 559 (C.D. Cal. 2021).
Furthermore, given that Defendant have not presented a record showing that the burden of this
discovery outweighs its likely benefit, Plaintiffs’ request that Defendants produce the agreements is
granted. Id. (After relevancy has been established, “[t]he party opposing discovery then has the burden of
showing that discovery should be prohibited, and the burden of clarifying, explaining or supporting its
objections.”). However, Defendants do not need to produce any “related communications” and are just
2 Of course, Judge Breyer may determine that this is not a type of loss that “the Copyright Act
properly protected” and thus not cognizable under the fair use analysis. Bartz v. Anthropic PBC, 787
F. Supp. 3d 1007, 1032 (N.D. Cal. 2025)
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required to produce executed agreements with third parties to obtain textual data for training purposes.
III. PATRICK WENDELL
Plaintiffs next request to add Patrick Wendell as a document custodian. Plaintiffs deposed
Mr. Wendell on December 4,2025, where he testified that he had a significant role in Databricks’
acquisition of MosaicML. See ECF No. 247-5 at 3 (explaining that he was “the primary member
of the leadership team evaluating whether we should do the acquisition, as well as understanding
what value Mosaic would bring to Databricks”). Plaintiffs then proceeded to request to add Mr.
Wendell as a document custodian on December 22, 2025. They argue that he “is likely to possess
unique documents related to Databricks’ motivation for the acquisition,” and request that
Defendants search Mr. Wendell’s custodial file for the period between May 1 to July 19, 2023
using the search string “Mosaic* AND (MPT* OR Storywriter*) AND (revenue* OR profit* OR
forecast* OR purchase OR acquisition OR acquire OR roadmap).” ECF No. 247-3 at 4.
Defendants oppose the request to add Mr. Wendell, arguing that the request is untimely and that
Plaintiffs’ apparent “regret” over “their choice of custodians” does not justify the late addition of a
new custodian. Id. at 6.
The undersigned agrees with Defendants. Although discovery is an iterative process, and
it is generally appropriate for parties to tailor requests based on what they learn earlier in
discovery, Plaintiffs have not shown that adding a new custodian at this late stage is warranted.
Plaintiffs may not have learned that Mr. Wendell was “the primary member of the leadership team
evaluating” the acquisition until December, but they knew he involved in the acquisition months
before that and delayed pursuing this matter. ECF No. 247-5 at 3; see ECF No. 178-6 (identifying
Wendell as a member of the “ring-fenced diligence group” evaluating the acquisition). The
discovery cutoff has now passed and adding a new document custodian now would unduly delay
the case schedule. Timeliness and diligence issues aside, other high-level executives involved in
the acquisition from both Databricks and MosaicML have been designated custodians and had
their custodial files combed through. See, e.g., ECF No. 130 (granting Plaintiffs’ request to
designate Databricks CEO Ali Ghodsi as a custodian), ECF No. 127. While Plaintiffs may be
correct that Wendell has “unique documents related to Databricks’ motivation for the acquisition,”
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it is also quite plausible that most of these documents were included in these other custodians’
files. ECF No. 247-3 at 4.
Plaintiffs’ request to add Patrick Wendell as a custodian is accordingly denied.
IV. CONCLUSION
Defendants shall respond to Interrogatory Nos. 42-50 and produce the executed agreements
for textual training data no later than January 30, 2026.
IT IS SO ORDERED.
Dated: January 16, 2026
LISA J. CISNEROS
United States Magistrate Judge
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