Hamrit v. Citigroup Global Markets, Inc. et al

Filing 106

OPINION AND ORDER re: 83 MOTION in Limine to exclude testimony of Larry F. Stewart. filed by City Personal Wealth Management, Citigroup, Inc., Citigroup Global Markets, Inc..For these reasons, Citigroups motion is granted. Post-trial briefing remains due by January 31, 2025, with optional response briefs due by February 21, 2025. The Clerk of Court is respectfully directed to close Docket Number 83. SO ORDERED. (Signed by Judge John P. Cronan on 11/26/2024) (jca)

UNITED STATES DISTRICT COURT
SOUTHERN DISTRICT OF NEW YORK
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HOUSSAM EDDINE HAMRIT,
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Plaintiff,
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-v:
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CITIGROUP GLOBAL MARKETS, INC., et al.,
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Defendants.
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:
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22 Civ. 10443 (JPC)
OPINION AND
ORDER

JOHN P. CRONAN, United States District Judge:
Defendants Citigroup Global Markets, Inc., Citi Personal Wealth Management, and
Citigroup, Inc. (collectively, “Citigroup”) move in limine to exclude the proffered expert testimony
of Larry F. Stewart. Pro se Plaintiff Houssam Eddine Hamrit seeks to have the Court consider at
trial expert conclusions from Stewart on the issue of whether he entered into an arbitration
agreement with Citigroup when his online brokerage account was opened. For the following
reasons, the Court grants Citigroup’s motion.
I. Background
In its March 26, 2024 Opinion on Citigroup’s pending motion to compel arbitration, the
Court outlined the background of this dispute. See Hamrit v. Citigroup Glob. Mkts., Inc., No. 22
Civ. 10443 (JPC), 2024 WL 1312254 (S.D.N.Y. Mar. 26, 2024). The Court assumes the parties’
familiarity with that background. In that Opinion, the Court concluded that Hamrit had come
forward with some evidence to raise a dispute of material fact on whether the parties agreed to
arbitrate and that Citigroup failed to cast doubt on the plausibility of that evidence, and therefore
ordered a trial on that limited issue. Id. at *9. In reaching that result, the Court noted that Citigroup

had “attack[ed] Stewart’s qualifications and ask[ed] the Court to disregard his report,” which was
part of Hamrit’s opposition to Citigroup’s motion to compel. Id. at *6 n.8. The Court did not rely
on Stewart’s conclusions in the Opinion, but noted that Citigroup would have “the opportunity to
challenge Stewart’s ability to provide expert testimony [at trial], should Hamrit wish to call Stewart
as a witness.” Id. Following the March 26, 2024 Opinion, the parties conducted limited discovery
in preparation for a bench trial on whether Hamrit entered into an arbitration agreement with
Citigroup.
On August 29, 2024, Citigroup moved in limine to exclude Stewart’s anticipated testimony
under Federal Rule of Evidence 702. Dkt. 85 (“Motion”). Hamrit filed his opposition on
September 12, 2024. Dkt. 90 (“Opposition”). 1 Citigroup filed a reply declaration on September
19, 2024. Dkt. 91 (“Reply”). “Because [the defendants’] Daubert challenge[ was] raised just prior
to trial and this trial was conducted as a bench trial, the court elected to hear the Daubert proof
during the trial itself.” Howard Univ. v. Borders, No. 20 Civ. 4716 (LJL), 2022 WL 11817721, at
*10 (S.D.N.Y. Oct. 20, 2022) (internal quotation marks omitted). “Although a court has general
discretion to hear expert testimony and reserve [ruling] on a Daubert motion until the conclusion
of a bench trial, it still must perform a Rule 702 and Daubert analysis before it relies upon expert
testimony.” Town & Country Linen Corp. v. Ingenious Designs LLC, No. 18 Civ. 5075 (LJL),
2022 WL 2757643, at *3 (S.D.N.Y. July 14, 2022). Trial in this matter commenced on October

1

The Court construes Hamrit’s pro se opposition to Citigroup’s motion liberally and
interprets his filings and arguments in court to raise the “strongest arguments that they suggest.”
Triestman v. Fed. Bureau of Prisons, 470 F.3d 471, 474 (2d Cir. 2006) (per curiam) (internal
quotation marks omitted) (collecting cases); accord Rahmankulov v. United States, Nos. 23 Civ.
3206 (RA), 20 Cr. 653 (RA), 2023 WL 3303949, at *1 (S.D.N.Y. May 8, 2023) (explaining that
while the Court must construe pro se pleadings liberally, “a pro se litigant is not exempt ‘from
compliance with relevant rules of procedural and substantive law’” (quoting Triestman, 470 F.3d
at 477)).
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22, 2024, and the Court, reserving a ruling on the pending motion in limine, heard Stewart’s
testimony on October 25, 2024. 2
Hamrit seeks to offer expert conclusions from Stewart that fall into two buckets. First,
Stewart testified that the security standards Citigroup employed did not align with those of the
National Institute of Standards and Technology (“NIST”) for high value transactions. Trial Tr. at
299:17-300:4, 319:6-11; see also Pl. Exh. 9 (“Stewart Report”) at 12 (citing NIST’s Digital
Identity Guidelines). Second, Stewart concluded that Citigroup’s system did not truly verify
Hamrit’s identity given discrepancies in the account opening documentation. 3 Trial Tr. at 318:23319:5; accord Stewart Report at 14 (“[I]t is my expert opinion that in light of the inadequacies and
abnormalities in the evidence as enumerated above, the [Account Application and Client
Agreement] are not reliable as conclusive proof of Mr. Hamrit’s electronic signature.”).
II. Legal Standard
Federal Rule of Evidence 702 provides:
A witness who is qualified as an expert by knowledge, skill, experience, training,
or education may testify in the form of an opinion or otherwise if the proponent
demonstrates to the court that it is more likely than not that:
(a) the expert’s scientific, technical, or other specialized knowledge will help
the trier of fact to understand the evidence or to determine a fact in issue;

2

The transcript of the bench trial is at Docket Numbers 100, 102, and 104. In this Opinion,
the trial transcripts are collectively referred to as “Trial Tr.” and the parties’ trial exhibits are
referred to as “Pl. Exhs.” and “Defts. Exhs.”
In addition to Stewart’s testimony, Hamrit sought to introduce into evidence several
declarations from Stewart and Stewart’s report. See Pl. Exhs. 8, 9, 22, 23. The Court accepted
these exhibits contingent on whatever weight they should receive following the Court’s resolution
of Citigroup’s motion in limine. Trial Tr. at 302:23-25; see also id. at 326:14-17.
3

According to Citigroup, Hamrit completed and executed the Account Application and
Client Agreement when he created his online brokerage account on May 3, 2020. The Account
Application and Client Agreement was admitted at trial as Defendants’ Exhibit 1. At the core of
the trial is whether Hamrit agreed to an arbitration clause contained at section 6 of that document.
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(b) the testimony is based on sufficient facts or data;
(c) the testimony is the product of reliable principles and methods; and
(d) the expert’s opinion reflects a reliable application of the principles and
methods to the facts of the case.
Fed. R. Evid. 702. “The fundamental requirements are thus that such evidence be relevant and
reliable.” United States v. Jones, 965 F.3d 149, 161 (2d Cir. 2020) (citing Daubert v. Merrell Dow
Pharms., Inc., 509 U.S. 579 (1993); Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999)).
“[T]he proponent of expert testimony has the burden of establishing by a preponderance of
the evidence that the admissibility requirements of Rule 702 are satisfied,” although “the district
court is the ultimate gatekeeper.” Id. (internal quotation marks omitted). This role requires the
district court to find that any admitted expert testimony “is not only relevant, but reliable.”
Daubert, 509 U.S. at 589. “Relevancy is determined by whether the proffered evidence ‘has any
tendency to make the existence of any fact that is of consequence to the determination of the action
more probable or less probable.’” Town & Country Linen Corp., 2022 WL 2757643, at *2 (quoting
Amorgianos v. Amtrak, 303 F.3d 256, 265 (2d Cir. 2002)). Reliability, meanwhile, encompasses
“a number of factors . . . that district courts may consider,” and is designed to be a flexible standard,
“focus[ed] on the principles and methodology employed by the expert, without regard to the
conclusions the expert has reached or the district court’s belief as to the correctness of those
conclusions.” Amorgianos, 303 F.3d at 266. “[W]hen an expert opinion is based on data, a
methodology, or studies that are simply inadequate to support the conclusions reached, Daubert
and Rule 702 mandate the exclusion of that unreliable opinion testimony.” Id.
III. Discussion
Citigroup argues that Stewart is not qualified to offer an opinion regarding the financial
technology matters relevant to whether Hamrit electronically executed the arbitration agreement,
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Motion at 4-5, and also contends that Stewart’s testimony would not be helpful to the trier of fact
as his opinions did not stem from any specialized expertise but instead merely convey lay
observations, id. at 6-7.
A. Qualifications
“Rule 702 requires a trial court to make an initial determination as to whether the proposed
witness qualifies as an expert.” Am. Empire Surplus Lines Ins. Co. v. J.R. Contracting & Env’t
Consulting, Inc., No. 23 Civ. 4942 (AT) (SDA), --- F. Supp. 3d ---, 2024 WL 3638329, at *5
(S.D.N.Y. Aug. 2, 2024) (internal quotation marks omitted). “As a threshold matter, trial courts
must consider whether the witness is qualified by knowledge, skill, experience, training, or
education to render his or her opinions as an expert, before reaching an analysis of the testimony
itself.” Vale v. United States, 673 F. App’x 114, 116 (2d Cir. 2016).
Citigroup contends that Stewart is not qualified to offer an expert opinion concerning
whether Hamrit electronically executed an arbitration agreement because he “has no demonstrated
expertise in cybersecurity, financial technology, opening of online accounts, or computer science
generally.” Motion at 5. Instead, Citigroup maintains that Stewart’s “expertise is limited to
handwriting, ink, document analysis and crime scene investigations.” Id. “To determine whether
a witness qualifies as an expert, courts compare the area in which the witness has superior
knowledge, education, experience, or skill with the subject matter of the proffered testimony.”
United States v. Tin Yat Chin, 371 F.3d 31, 40 (2d Cir. 2004).
At trial, Stewart explained that he is “a forensic scientist that specializes in chemistry and
document security.” Trial Tr. at 282:5-7. And Stewart does appear to have expertise in these areas
from his experience, training, and education. See id. at 282:8-283:6 (Stewart testifying about his
education, certification, and membership in professional associations), 283:24-284:19 (Stewart

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describing his training, publications, and membership on boards in this field). When questioned
by Citigroup’s counsel on voir dire, Stewart further testified that, in his prior role as a laboratory
director with the United States Secret Service, 4 he supervised the “digital evidence laboratory” and
reviewed analytic work on that subject, although he did not perform the primary analysis. Id. at
288:15-25.
While Citigroup correctly notes Stewart’s lack of expertise in computer science, financial
technology, or cybersecurity, Hamrit offered Stewart at trial as an expert in “document security.”
Id. at 286:17-19; see also Opposition at 4-7. When asked what he understood the term “document
security” to mean, Stewart testified that “[t]here are a number of levels of security that are attached
to documents at the federal level which is where I work. NIST is one of the main ones that
designate the security involved in documents. And also a group called FinCEN. Those are in
addition to the FinTech he’s mentioning, which is mainly for bank fraud situations.” Trial Tr. at
291:10-19. Stewart explained that at the Secret Service, he dealt with document security issues
and received training in “all aspects of documents from passports to personal documents like
driver’s licenses and identity documents that can be created either online or manually using
devices,” as well as in investigating financial institution fraud involving digital systems. Id. at
292:4-19. Stewart’s most recent formal training in this area, though, was in the 1990s. Id. at
292:21-25. Nonetheless, “[e]ven if a proposed expert lacks formal training in a given area, he may
still have ‘practical experience’ or ‘specialized knowledge’ qualifying him to give opinion
testimony under Rule 702.” Lickteig v. Cerberus Cap. Mgmt., L.P., 589 F. Supp. 3d 302, 328
(S.D.N.Y. 2022).

4

According to Stewart’s resume, he held various positions with the Secret Service from
July 1982 through June 2005. Pl. Exh. 8 (“Stewart July 28, 2023 Declaration”) at 57.
6

The parties disagree on whether Stewart’s experiences qualify him to offer an expert
opinion on the narrow issue of the trial: whether Hamrit electronically executed an arbitration
agreement with Citigroup when his online brokerage account was opened. Compare Motion at 5,
with Opposition at 6-7. In the end, the Court need not determine the full reach of Stewart’s
expertise. As will be explained at infra III.B, the opinions Stewart seeks to offer do not survive
Rule 702 on relevance or reliability grounds, and thus must be excluded regardless of his expert
qualifications. The Court therefore will assume without deciding that Stewart has expertise in the
proffered field of “document security” for Rule 702 purposes.
The Court emphasizes one caveat to this assumption, however. A key piece of evidence in
this case is a document called a ThreatMetrix report. See Defts. Exh. 4. One of Citigroup’s
witnesses at trial, a Citigroup fraud risk officer named Eustacio Valfre, explained that this report
captures “[e]ach digital session” that a client has on Citigroup’s online platform and that the report
“has a bunch of different data points that [Citigroup’s fraud officers] review” when assessing fraud
risk. Trial Tr. at 94:5-95:3. Valfre testified that these reports include certain “digital evidence,”
such as the “time that a person may have logged in on their account, [the] account user ID that was
used, the time that it was accessed, what was done within that session, and how that session was
authenticated.” Id. at 96:4-7. The ThreatMetrix report captures “session information, such as a
unique session ID[,] . . . geo location, which would be IP address, true IP address, and DNS IP
address[,] . . . latitude and longitude[,] . . . transaction information, what was done within that
session, if there was any type of transfers, and such. And then you have an authentication [the
user] used, or any challenges, and how they were passed.” Id. at 96:8-14. Valfre also testified that
Citigroup’s fraud risk officers receive six weeks of training on the ThreatMetrix product and other
fraud prevention tools, which enables them to “review and analyze data that [Citigroup is] seeing

7

in our digital space,” and that the training includes “the usage and the review of the data fields that
we receive, and using [Citigroup’s] tools, and how to interpret that information.” Id. at 90:6-23,
93:7-17.
It is unclear whether Stewart sought to offer his opinions based on the ThreatMetrix report,
or otherwise to opine on the contents of the report. Indeed, Stewart does not identify the
ThreatMetrix report in his own purported expert report among the materials he reviewed in arriving
at his conclusions, see Stewart Report at 1-2, 5 nor does he reference the ThreatMetrix report in his
report’s “Observations,” see id. at 2-14. Yet, at trial, Stewart testified that he reviewed the
ThreatMetrix report in preparing his report. Trial Tr. at 296:6-9. To be sure, however, Stewart
lacks “knowledge, skill, experience, training, or education,” Fed. R. Evid. 702, to offer opinions
based on the ThreatMetrix report or concerning its contents, as the Court ruled at trial, Trial. Tr.
at 306:11-307:6.
“[B]ecause a witness qualifies as an expert with respect to certain matters or areas of
knowledge, it by no means follows that he or she is qualified to express expert opinions as to other
fields.” Nimely v. City of New York, 414 F.3d 381, 399 n.13 (2d Cir. 2005). And Stewart plainly
is not qualified to offer an expert opinion regarding the ThreatMetrix report. During voir dire,
Stewart testified that he has never received any training concerning ThreatMetrix, has never
offered an opinion concerning ThreatMetrix, and has never drafted a report concerning
ThreatMetrix. Trial Tr. at 289:5-13. Nor did Hamrit otherwise offer any information indicating
Stewart’s training or experience with regard to ThreatMetrix. Given Stewart’s testimony, the

5

Hamrit’s Opposition also indicates that Stewart had not reviewed the ThreatMetrix report
prior to preparing his report for this case. See Opposition at 9 (complaining that “Mr. Stewart must
be allowed the opportunity to review, analyze and testify about” the ThreatMetrix report); see also
Reply, Exhs. B, C (establishing that, contrary to Hamrit’s gripes, the ThreatMetrix report was
disclosed during discovery).
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limits of his training and experience, and his lack of familiarity with the ThreatMetrix product, the
Court reiterates its determination that Stewart is not qualified to offer testimony that would aid the
Court’s assessment of the ThreatMetrix report. See id. at 306:13-307:6 (the Court observing, after
hearing Stewart’s testimony, that Stewart “very clearly testified that he has no training concerning
ThreatMetrix, [has] not offered any opinion in the past” concerning ThreatMetrix, and has “never
drafted a report concerning” ThreatMetrix, and thus “[a]nything Mr. Stewart would testify about
that report is something that [the Court is] able to derive from the report that’s already in
evidence”).
The Court acknowledges that “[i]f the expert has educational and experiential
qualifications in a general field closely related to the subject matter in question, the court will not
exclude the testimony solely on the ground that the witness lacks expertise in the specialized areas
that are directly pertinent.” Am. Empire Surplus Lines Ins. Co, 2024 WL 3638329, at *5 (internal
quotation marks omitted). But to be sure, that is not the case when it comes to the ThreatMetrix
report. And the Court’s focus remains on “whether the expert’s knowledge of the subject is such
that his opinion will likely assist the trier of fact in arriving at the truth.” Id. (internal quotation
marks omitted).

Stewart’s purported expertise in “document security” was devoid of any

knowledge or training that would allow him to opine on the probative value of the information in
a technical product like the ThreatMetrix report that captures a variety of pieces of digital evidence
and requires specialized training to properly understand and interpret.
In sum, the Court will assume without deciding that Stewart possesses expert qualification
to testify on matters in this case, with the understanding that he may not base any opinions on the
ThreatMetrix report or opine on its contents.

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B. Relevance and Reliability
Even assuming arguendo Stewart’s expertise in document security, his proffered expert
testimony fails the relevance and reliability requirements of Rule 702. Starting with relevance,
Rule 702(a) requires that the expert’s knowledge “help the trier of fact to understand the evidence
or to determine a fact in issue.” Fed. R. Evid. 702(a). This requirement “goes primarily to
relevance.” In re Fosamax Prods. Liab. Litig., 645 F. Supp. 2d 164, 173 (S.D.N.Y. 2009) (citing
Daubert, 590 U.S. at 591). But “expert testimony is not helpful if it simply addresses ‘lay matters
which the [finder of fact] is capable of understanding and deciding without the expert’s help.’” Id.
(quoting United States v. Lumpkin, 192 F.3d 280, 289 (2d Cir. 1999)). And “[a] court should not
admit expert testimony that is ‘directed solely to lay matters which a [finder of fact] is capable of
understanding and deciding without the expert’s help.’” Pacific Life Ins. Co. v. Bank of N.Y.
Mellon, 571 F. Supp. 3d 106, 114 (S.D.N.Y. 2021) (quoting United States v. Mulder, 273 F.3d 91,
104 (2d Cir. 2001)).
Almost all of Stewart’s proffered testimony falls into this category of matters that the Court
is fully capable of understanding without assistance from an expert. Stewart explained that his
methodology entailed “first examining the submitted Account Application and Client Agreement
followed by an analysis of the submitted supportive documentation and self-obtained data. The
results were then compared and presented here.” Stewart Report at 2; Stewart July 28, 2023
Declaration ¶ 7. In other words, Stewart looked at two documents and observed that some of the
information in each was different. From this method, Stewart concluded that Citigroup’s system
did not “truly verif[y] the identity of Mr. Hamrit,” Trial Tr. at 318:23-319:5, and that the Account
Application and Client Agreement “are not reliable as conclusive proof of Mr. Hamrit’s electronic
signature,” Stewart Report at 14.

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The Court, of course, is well-equipped to do the same analysis. It requires no expertise,
for example, to observe that Hamrit’s “residential address at the date of the Account Application
and Client Agreement was different from the residential address stated therein,” that Hamrit’s
“immigration status is different from that stated in the Account Application and Client
Agreement,” or that a document has “different fonts,” contains a “blurred image,” or lacks a
signature. Stewart July 28, 2023 Declaration ¶ 9; see also Stewart Report at 2-10 (providing these
and other examples of discrepancies, such as different spellings of Hamrit’s mother’s maiden name
on the Account Application and Client Agreement and on Hamrit’s birth certificate). These are
simply lay observations concerning the contents of two documents, which in no way rely on
Stewart’s purported expertise in document security. See Pacific Life Ins. Co., 571 F. Supp. 3d at
114. Moreover, this methodology directly led Stewart to draw a conclusion that a layperson,
lacking expertise in document security, would reach: discrepancies between the documents raise a
question of their authenticity. See Atl. Specialty Ins. v. AE Outfitters Retail Co., 970 F. Supp. 2d
278, 291-92 (S.D.N.Y. 2013) (excluding expert testimony on the subject of fire damage on the
grounds that “the mere fact that a fire causes increasing damage the longer it burns is an obvious
statement, and a lay person is entirely capable of reaching this conclusion without the help of an
expert”).
Stewart’s purported opinion that Citigroup did not verify Hamrit’s identity because there
were discrepancies in the account opening documentation, therefore, does not rely on any expertise
but is drawn from lay matters that the Court is “capable of understanding and deciding without the
expert’s help.’” Pacific Life Ins. Co., 571 F. Supp. 3d at 114 (quoting Mulder, 273 F.3d at 104).
Because Stewart’s observations and conclusions in this regard do not “help the [Court] to

11

understand the evidence or to determine a fact in issue,” Fed. R. Evid. 702(a), they fail the
helpfulness requirement of Rule 702 and are excludable on that basis.
Moreover, Stewart’s proffered expert testimony suffers from reliability concerns. Rule
702(b) requires that an expert’s testimony be “based on sufficient facts or data.” Fed. R. Evid.
702(b). The undisputed evidence at trial, however, makes clear that Stewart’s testimony and
conclusions repeatedly were predicated on insufficient facts and invalid assumptions.
Most significantly, Stewart’s proffered conclusion that Citigroup’s security standards were
insufficient relied on a fundamentally flawed premise as he assumed the absence of biometric
authentication. Stewart testified that Hamrit’s purported account-opening transaction did not
comply with the standards of the NIST for large dollar transactions. Trial Tr. at 299:17-300:4.
Stewart reasoned in his report that Citigroup’s failure to use such standardized measures, like
private encryption keys and electronic signature authentications, undermine confidence that
Hamrit in fact entered into the arbitration agreement. Stewart Report at 10-14. But at trial, when
asked whether he would have concerns with security if someone accessed their account via
“biometrics through using face ID,” Stewart replied, “No. As you add additional security through
face identification or, you know, a two-step process, like they have in a lot of different situations
now, that adds security to it.” Trial Tr. at 300:22-301:7. Stewart remarked, however, that he saw
“no evidence of that being done here.” Id. at 301:7. Stewart later acknowledged on crossexamination that using face identification to log in in this manner “would be an added measure of
security,” which he would consider to be “pretty strong.” Id. at 313:6-13; see also id. at 319:4-5
(Stewart testifying that he “saw no evidence of multifactor authentication . . . based on what was
provided to [him]”).

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Yet, the undisputed evidence at trial established that Hamrit’s account had in place
biometric identification for access and that such access was indeed used when his online brokerage
account was opened. When asked during cross-examination if he had “registered [his] online
accounts so [he] could log in using facial ID,” Hamrit admitted, “I have face ID. Yes, I have face
ID.” Id. at 242:7-12. Hamrit also testified that he had registered his online accounts to use face
identification before May 3, 2020, the date of the transaction opening his brokerage account. Id.
at 242:14-18. Valfre testified that the ThreatMetrix report logged a biometric login during the
digital session in which the brokerage account was opened. Id. at 97:21-25 (“I can see that this
session on 5/3 began with user ID Houssam10, with that unique ID number under column C. And
this was the initial login, and it was a biometric login. It was a face ID so, basically, holding a
phone up or camera, and facial recognition to log in, to authenticate.”), 98:11-13 (“Q. And he
logged in using facial recognition, not using a password; is that correct? A. That’s correct.”). The
ThreatMetrix report itself likewise established that biometric identification was used to initiate that
account-opening session. See Defts. Exh. 4, Rows 103-104 (indicating a face identification login
to begin an online session on May 3, 2020, five minutes before the brokerage account was opened).
Indeed, the ThreatMetrix report is replete with face identification logins. See generally id.
Stewart’s conclusion that Citigroup’s security standards did not meet those of the NIST thus rested
on the faulty assumption that there was no evidence of Hamrit having biometric access to his
accounts or that such biometric access was used to initiate the session when Hamrit’s brokerage
account was opened.
This is not the only instance of Stewart basing his testimony on insufficient or incomplete
information to draw conclusions regarding the authenticity of the records at issue. Stewart testified
about font issues and the “fuzzy” background on the Client Agreement. Trial Tr. at 318:14-17.

13

Stewart said he was “not sure how that was created, whether it was a cut and paste from another
document or electronically generated by Citigroup. But if it was electronically created, [he] would
ask for an explanation as to why there is a difference in the quality between that and the rest of the
document.” Id. at 318:17-22. Matthew Higman, a Citigroup employee familiar with the bank’s
digital wealth products, testified that this effect occurs because when a customer “signs” their
name by typing it into the agreement, Citigroup takes an image of what they typed to use as the
customer’s “signature” and renders that along with the date they typed in as evidence of signature.
Id. at 33:13-34:21.

No evidence at trial contradicted this testimony.

While it may be

understandable why Stewart lacked familiarity with Citigroup’s internal procedures, this too
demonstrates that his conclusions relied on insufficient facts and flawed assumptions.
“Where the record indicates that the expert’s analysis rests on faulty assumptions, the trial
court has discretion to exclude his proffered testimony for lack of probative value.” Bank of N.Y.
Mellon Tr. Co., Nat. Ass’n v. Solstice ABS CBO II, Ltd., 910 F. Supp. 2d 629, 649-50 (S.D.N.Y.
2012) (alterations adopted) (collecting cases). Here, Stewart’s failure to base his conclusions on
complete and accurate information severely diminishes any probative value of his testimony. And
in particular, Stewart’s flawed assumption that biometric access was not in place when Hamrit’s
online brokerage account was opened, in the face of overwhelming and undisputed evidence to the
contrary, renders his conclusion about whether Citigroup met the NIST’s standards devoid of any
probative value and require exclusion of that conclusion.
The Court therefore finds that Stewart’s conclusions that Citigroup failed to employ
security standards that aligned with those of the NIST for high value transactions and that
Citigroup’s system did not truly verify Hamrit’s identity do not survive Rule 702(a) and Rule

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702(b). The Court thus excludes Stewart’s proffered expert testimony and strikes Hamrit’s
Exhibits 8, 9, 22, and 23 from the trial record.
IV. Conclusion
For these reasons, Citigroup’s motion is granted. Post-trial briefing remains due by January
31, 2025, with optional response briefs due by February 21, 2025. The Clerk of Court is
respectfully directed to close Docket Number 83.
SO ORDERED.
Dated: November 26, 2024
New York, New York

__________________________________
JOHN P. CRONAN
United States District Judge

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