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
In re Mosaic LLM Litigation
Case No. 24-cv-01451-CRB (LJC)
ORDER ADDRESSING DEPOSITION
CONDUCT
Re: Dkt. No. 194
Before the Court is the parties’ joint discovery letter brief regarding Defendants’ counsel’s
conduct during depositions. ECF Nos. 192-2, 194.1 The Court assumes the parties’ familiarity
with the procedural and factual background of the case, as well as the details of the deposition
conduct at issue.
Plaintiffs allege that Defendants’ counsel has engaged in “consistent” misconduct during
depositions by coaching witnesses during breaks and by improperly instructing witnesses not to
answer. ECF No. 192-2 at 2. Plaintiffs request a court order “(1) prohibiting counsel from
discussing the substance of testimony during deposition breaks except to address issues of
privilege; (2) requiring Defendants to make Hanlin Tang and Jonathan Frankle available for
additional depositions to respond to questions they were instructed not to answer; and
(3) requiring Defendants to cease directing witnesses not to answer for reasons other than
privilege, legitimate harassment, or in connection with a prior court order.” Id. The Court
1 The redacted letter brief is filed at ECF No. 194. The unredacted brief and exhibits are filed
under seal at ECF No. 192-2–192-9. In this Order, the Court cites to the versions under seal.
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United States District Court
Northern District of California
addresses these requests in turn.2
A. Conduct During Breaks in Depositions
“It is improper for a witness and her attorney to discuss the substance of her testimony
during breaks in a deposition, except where necessary to address matters of privilege.” Barajas v.
Abbott Lab’ys, Inc., No. 18-cv-00839, 2018 WL 6248550, at *4 (N.D. Cal. Nov. 29, 2018); see In
re Cathode Ray Tube (CRT) Antitrust Litig., No. 14-cv-2058, 2015 WL 12942210, at *3 (N.D.
Cal. May 29, 2015) (“[O]nce a deposition begins, counsel should not confer with the witness
except to determine whether a privilege should be asserted.”). The undersigned’s Standing Order
provides that “[p]rivate conferences between deponents and attorneys in the course of
interrogation, including a line of related questions, are improper and prohibited except for the sole
purpose of determining whether a privilege should be asserted.”
Consistent with the undersigned’s Standing Order and Northern District caselaw, counsel
may not discuss the substance of a witness’s testimony with the witness during breaks in a
deposition, except for the purpose of determining whether a privilege should be asserted. If
counsel believes that a witness’s testimony requires clarification or needs to refresh the witness’s
recollection, the proper procedure is for them to question the witness “on the record at the
conclusion of the deposition” rather than confer with the witness during breaks. Barajas, 2018
WL 6248550, at *4. Counsel shall comply with these procedures at any future depositions.3
This raises the related question of whether witnesses must answer questions regarding
communications with counsel during breaks. To permit the deposing counsel to confirm that the
deponent and their counsel comply with the Court’s prohibition above, the deposing counsel may
ask the deponent if they discussed the substance of their testimony (aside from where necessary to
address privilege issues) with their counsel during breaks in the deposition. The witness must
confirm or deny this but is not required to otherwise describe the content of their communications
2 The parties’ joint administrative motion to exceed the page limit for exhibits to discovery briefs
is granted. ECF No. 193.
3 Although the close of fact discovery was on November 21, 2025, the undersigned has provided
the parties until December 5, 2025, to complete five outstanding depositions. ECF No. 187.
Moreover, Plaintiffs have requested that the close of fact discovery be extended to January 5,
2026. See ECF No. 191.
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United States District Court
Northern District of California
with counsel. The witness’s confirmation or denial will not constitute a waiver of attorney-client
privilege.
Turning to Plaintiffs’ request that the depositions of Hanlin Tang and Jonathan Frankle be
continued to “respond to questions they were instructed not to answer” regarding communications
with their counsel during breaks in their depositions, the undersigned finds that continuing the
depositions on these grounds is not warranted. The transcript of Tang’s deposition indicates that,
after a break, he clarified what he meant when he had described certain datasets as being “public,”
which, as Defendants note, was consistent with his earlier testimony that the datasets were
accessible to those who had a link to the dataset. See ECF No. 192-3 at 2, 9. The Frankle
transcript indicates that Frankle was initially unable to respond to questions about the use of a
particular dataset, reviewed a document during a break, and then, when his attorney cross-
examined him at the end of the deposition, responded to the question regarding the dataset. See
ECF No. 192-7 at 6-7, 11.
To the extent Defendants’ counsel spoke with the witnesses about the substance of their
testimony during breaks, this conduct was improper, and the far better course would have been for
counsel to (in the case of Tang) cross-examine him about his use of the word “public” and (in the
case of Frankle) show him the document to refresh his recollection and question him on the record
during the deposition. But Tang did not retract his prior testimony or reverse course after a break.
Cf. Medicinova, Inc. v. Genzyme Corp., No. 14-CV-2513, 2021 WL 3054874, at *7 (S.D. Cal. July
20, 2021) (“[A] sharp contrast between responses before and after a break in testimony can
support an inference that the witness was improperly coached”). Plaintiffs questioned Frankle
about the document he reviewed during the break to refresh his recollection, and Frankle
responded to their questioning. ECF No. 192-7 at 15. In these circumstances, requiring the
witnesses to testify about their communications with counsel, which, as Defendants note, are
privileged, is not warranted. See Barajas, 2018 WL 6248550, at *4 (finding the deponent’s
counsel conduct improper but denying request for a further deposition where the deponent “did not
change her answer after communicating with counsel” and the deposing attorney had opportunity
to question the witness). Plaintiffs’ request that Tang and Frankle be made available for additional
depositions to respond to questions they were instructed not to answer regarding communications
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United States District Court
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with their counsel during breaks is accordingly denied.
B. Instructions Not to Answer
Plaintiffs separately argue that Defendants’ counsel improperly instructed witnesses not to
answer and request an order requiring Defendants to cease directing witnesses not to answer for
reasons other than privilege, legitimate harassment, or in connection with a prior court order.
Rule 30(c)(2) provides that a person defending a deposition “may instruct a deponent not
to answer only when necessary to preserve a privilege, to enforce a limitation ordered by the court,
or to present a motion under Rule 30(d)(3).” In turn, Rule 30(d)(3) permits deponents and parties
to move to terminate or limit a deposition on “the ground that it is being conducted in bad faith or
in a manner that unreasonably annoys, embarrasses, or oppresses the deponent or party.” “As a
rule, instructions not to answer questions at a deposition are improper,” except as provided by
Rule 30(c)(2). Detoy v. City & Cnty. of San Francisco, 196 F.R.D. 362, 365 (N.D. Cal. 2000).
The undersigned fully expects the parties to comply with Federal Rules and instruct witnesses not
to answer only in the narrow circumstances permitted under Rule 30(c)(2).
Plaintiffs take issue with Defendants’ counsel’s instructions to their witnesses not to
answer questions regarding (1) DBRX training data, (2) witnesses’ personal experience using
media-sharing websites such as Napster, and (3) witnesses’ finances. The undersigned has ruled
that discovery regarding DBRX training data is not warranted at this stage in the case, and Judge
Breyer previously denied Plaintiffs’ request to further amend their complaint so that they could
“proceed with discovery as to the DBRX models.” ECF Nos. 163, 162 at 5. In light of these prior
orders limiting Plaintiffs’ discovery regarding the DBRX models, Defendants’ counsel’s
instruction to Frankle not to answer questions regarding DBRX training data was appropriate
under Rule 30(c)(2). See ECF Nos. 162, 163, 192-7 at 9.
Plaintiffs’ questions regarding witnesses’ experience torrenting media and using websites
such as Napster, while perhaps seeking information only marginally relevant to this case, did not
“unreasonably annoy[], embarrass[], or oppress[] the deponent[s].” Fed. R. Civ. P. 30(d)(3).
Counsel’s instruction to Naveen Rao not to answer—based on his objection that it was not
“appropriate to ask a witness personal questions” rather than based on an applicable privilege or
other grounds authorized under Rule 30(c)(2)—was accordingly improper. ECF No. 192-5 at 3-4;
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United States District Court
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see Toman v. Glomboske, No. 20-cv-00046, 2021 WL 3503062, at *4 (C.D. Cal. Mar. 25, 2021)
(“Thus, to prevail, Plaintiff must establish more than that the disputed questions seek irrelevant
information … Plaintiff must establish that the disputed deposition questions concern subjects so
sensitive that answering them would unreasonably annoy, embarrass, or oppresses her.”)
(quotation marks omitted).
Plaintiffs’ questions regarding witnesses’ personal finances implicate the witnesses’
privacy concerns, but, as Plaintiffs argue, testimony regarding witnesses’ financial benefit from
Databricks’ acquisition of MosaicML may be relevant to their claims. Moreover, as the
deposition transcripts appear to be designated as Attorney-Eyes’ Only, Defendants’ privacy
concerns are somewhat overblown. The Court accordingly finds that Defendants’ instructions to
Tang not to answer questions regarding his stake in MosaicML at the time of the acquisition and
how much he made as a result of the acquisition were improper. See ECF No. 192-3 at 25-29.
The Court notes that this does not give Plaintiffs carte blanche to question witnesses regarding
their personal finances unrelated to the acquisition or the financial benefit from Defendants’
alleged infringement, and instructions not to answer may be appropriate in such situations.
The parties are accordingly ordered to comply with Rule 30(c)(2). Instructing a witness
not to answer a question posed during a deposition is only appropriate “when necessary to
preserve a privilege, to enforce a limitation ordered by the court, or to present a motion under Rule
30(d)(3).” Fed. R. Civ. P. 30(c)(2).
IT IS SO ORDERED.
Dated: November 25, 2025
LISA J. CISNEROS
United States Magistrate Judge
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