United States of America v. Cornelius M. Jackson

In the
United States Court of Appeals
For the Seventh Circuit
____________________
Nos. 24-1776 & 24-2260
U NITED S TATES OF A MERICA,
Plaintiff-Appellee,
v.
C ORNELIUS M. JACKSON ,
Defendant-Appellant.
____________________
Appeals from the United States District Court for the
Eastern District of Wisconsin.
No. 2-20-cr-00229 — Brett H. Ludwig, Judge.
____________________
A RGUED J ANUARY 29, 2026 — DECIDED J UNE 22, 2026
____________________
Before R IPPLE, LEE, and K OLAR , Circuit Judges.
R IPPLE, Circuit Judge. A jury convicted Cornelius M. Jack-
son of four counts of sex trafficking and one count of conspir-
acy to commit sex trafficking. He now contends that the initial
search warrant application was not supported by probable
cause, that the district court erred by denying him a Franks
hearing because the affidavit supporting the warrant applica-
tion contained material omissions, and that the district court
should not have permitted the Government’s expert witness

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2 Nos. 24-1776 & 24-2260
to testify at trial. For the reasons set forth in this opinion, we
affirm the judgment of the district court.
I
BACKGROUND
At around 5:00 a.m. on August 23, 2020, Milwaukee Police
Officer James Pittman was dispatched to East Brady Street to
investigate calls from two people. The first caller, later identi-
fied in this case as AV-4, reported that her belongings had
been stolen and that she had been left in an unfamiliar area by
the people with whom she had been staying. The other caller
reported that he had seen a man throw a woman down and
thought that man might be the woman’s “pimp.”
Officer Pittman approached AV-4 when he arrived on the
scene. But there was another woman on the street who at-
tempted to interfere with Officer Pittman’s interaction with
AV-4. At first, AV-4 told him that she had called the police to
report her stolen items and that no one was trying to hurt her.
Apparently not accepting her account on face value, Officer
Pittman pretended to arrest her in order to take her some-
where safe.
Once in a police van, AV-4 told Officer Pittman that she
had never engaged in prostitution and that “everything was
going fine” with Mr. Jackson and the other women with
whom she had been living.1 With additional questioning,
however, AV-4 told Officer Pittman that Mr. Jackson had
choked her to unconsciousness while two women yelled at
her. During this interview, other officers informed Officer
Pittman that pole camera footage corroborated AV-4’s
1 R.70 at 4.

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Nos. 24-1776 & 24-2260 3
account. AV-4 told Officer Pittman that Mr. Jackson had
threatened to kill her, wanted to control her activities, and
kept a firearm in his home. She also explained that Mr. Jack-
son had told her he wanted her to “work for what she’s
worth,” and described to the officers the hours and pricing for
sex work that he required her to perform.2
Because he suspected sex trafficking, Officer Pittman noti-
fied the Sensitive Crimes Division of the Milwaukee Police
Department. A few hours after Officer Pittman’s arrival on the
scene, Officer Gerardo Orozco of that division arrived and
more thoroughly interviewed AV-4. AV-4 explained that she
had met Mr. Jackson on a dating application, provided a de-
scription of the car he had used to pick her up, and said that
he had called for three other women to “hang out” with her
at a hotel room. Then, AV-4 was required to leave the room
when men came into the room with the other women. AV-4
spent the next two and a half weeks at Mr. Jackson’s
Waukesha residence, where Mr. Jackson told her she had to
make money to pay the bills. She conducted six “dates” at the
residence; each involved engaging in sex acts for money.
Mr. Jackson required her to give him all her earnings. On the
night of her encounter with Officer Pittman, AV-4 had trav-
eled to downtown Milwaukee with Mr. Jackson and a few
other women.
Officer Orozco’s interview with AV-4 served as the basis
for Waukesha Detective Kenny Stucker’s application for a
search warrant for Mr. Jackson’s Waukesha address and the
seizure of electronic devices inside. The affidavit supporting
the application recites that Detective Stucker received a report
2 Id.

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4 Nos. 24-1776 & 24-2260
from the Milwaukee Police Department of “strangulation/suf-
focation and human trafficking.”3 The affidavit did not report
that AV-4 first told Officer Pittman that no one was trying to
hurt her or that she disclosed Mr. Jackson’s conduct only after
Officer Pittman had pretended to arrest her. It did explain,
however, that the women were required to text Mr. Jackson
about everything that transpired with their “dates” and to ob-
tain photos of the men’s genitals and middle fingers. It also
described Mr. Jackson’s control of advertisements and escort
conversations on websites for escort and prostitution services.
It included Detective Stucker’s personal knowledge that “in-
dividuals engaging in commercial sex trafficking typically
utilize log books and client databases whether written or elec-
tronic to schedule dates and further the ends of their enter-
prise.”4
A judicial officer granted a search warrant based on the
application. On August 27, 2020, law enforcement officers ex-
ecuted the warrant at Mr. Jackson’s residence and on his ve-
hicle parked there. The officers recovered nineteen cell
phones and other electronic devices and ammunition. They
also retrieved identification and bank cards for individuals
who did not live there. A grand jury later indicted Mr. Jack-
son. The indictment accused him of running a sex trafficking
operation from March 2014 through August 2020 in the East-
ern District of Wisconsin, the District of Minnesota, the Dis-
trict of North Dakota, and the Northern District of Ohio. More
specifically, the grand jury indicted him on four counts of sex
trafficking by force, fraud, or coercion, in violation of 18
3 R.55-3 at *6, ¶ 2.
4 Id. at *8, ¶ 17.

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Nos. 24-1776 & 24-2260 5
U.S.C. § 1591(a)(1) and (b)(1), and one count of conspiracy to
engage in sex trafficking, in violation of 18 U.S.C. § 1594(c).
After a trial, Mr. Jackson was convicted on all five counts. The
district court sentenced him to 30 years’ imprisonment on
each count, to run concurrently, and 10 years of supervised
release.
II
DISCUSSION
Mr. Jackson asks us to review the district court’s denial of
his pre-trial motion to suppress evidence obtained from his
cell phone under the search warrant and the denial of his mo-
tion for a Franks hearing. He also maintains that the district
court abused its discretion when it permitted the Govern-
ment’s expert witness to testify at trial.
A
We first address Mr. Jackson’s contention that the district
court should have excluded all the evidence derived from the
search of his cell phone. He contends that there was no nexus
between his cell phone and the criminal behavior under in-
vestigation. In reviewing a denial of a motion to suppress ev-
idence, we review legal questions de novo and factual deter-
minations for clear error. United States v. Dixon, 137 F.4th 592,
601 (7th Cir. 2025).
Before the district court, Mr. Jackson contended that the
search warrant did not set forth a sufficient nexus between his
electronic devices and human trafficking. The district court
concluded that this argument found no support in the record.
Referring to the affidavit supporting the application for a
search warrant, the court noted the description of Mr. Jackson
having met AV-4 on a dating application, his creation of her

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6 Nos. 24-1776 & 24-2260
profile on an escort website, and his use of her pictures from
her phone for the profile. The court also noted that Detective
Stucker wrote that, according to his training and experience,
sex traffickers often use log books and client databases and
that these tools are sometimes electronic. Therefore, con-
cluded the court, there was a fair probability that evidence of
sex trafficking would appear on Mr. Jackson’s phone and
other electronic devices.
The Fourth Amendment requires probable cause to sup-
port a search warrant. When an affidavit is the only evidence
supporting a search warrant, the warrant’s validity depends
on the strength of the affidavit. United States v. Mykytiuk, 402
F.3d 773, 775 (7th Cir. 2005) (quoting United States v. Peck, 317
F.3d 754, 755–56 (7th Cir. 2003)). The affidavit establishes
probable cause when it “sets forth sufficient evidence to in-
duce a reasonably prudent person to believe that a search will
uncover evidence of a crime.” Id. at 776 (citation modified). A
finding of probable cause will be upheld so long as there was
a “‘substantial basis for … conclud[ing]’ that a search would
uncover evidence of wrongdoing.” United States v. Rees, 957
F.3d 761, 765 (7th Cir. 2020) (quoting Illinois v. Gates, 462 U.S.
213, 236 (1983)). This analysis is “not technical” and considers
the totality of circumstances. United States v. Hicks, 650 F.3d
1058, 1065 (7th Cir. 2011).
Mr. Jackson argues that there was no nexus between his
electronic devices and the sex trafficking because the only cell
phone cited in the affidavit was AV-4’s phone, not Mr. Jack-
son’s.
While the affidavit described Mr. Jackson’s use of AV-4’s
cell phone to set up an escort profile for her online, it also ex-
plained that AV-4 met Mr. Jackson on a digital dating

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Nos. 24-1776 & 24-2260 7
application. And it stated that AV-4 was instructed to text
Mr. Jackson during every “date” to tell him if the situation
was good or bad.5 The affidavit therefore supported that
Mr. Jackson was using at least one electronic device to recruit
and communicate with potential victims and to help monitor
the “dates.”
Mr. Jackson also submits that Detective Stucker’s experi-
ence “on a wide array of crimes including sexual assault of
children” did not sufficiently qualify him to assess reliably
whether Mr. Jackson was engaged in human trafficking or
whether a search of his electronic devices would reveal evi-
dence of those crimes.6 But this argument invites us to impose
the sort of “hypertechnical” analysis that we found inappro-
priate to invalidate a warrant in Hicks, 650 F.3d at 1066. As we
said there, “[p]robable cause determinations are not technical;
rather, they are the factual and practical considerations of eve-
ryday life” and, when evaluated through that lens, we think
that the detective’s experience was both relevant and proba-
tive to the task before the district court. Id. at 1065 (citation
modified). Indeed, it was this very background that allowed
the detective to assert that he was “aware that individuals en-
gaging in commercial sex trafficking typically utilize log
books and client databases whether written or electronic to
schedule dates and further the ends of their enterprise.”7 This
statement by the detective explains the relevance of AV-4’s
5 Id. at *8, ¶ 13.
6 Id. at *6, ¶ 1.
7 Id. at *8, ¶ 17.

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8 Nos. 24-1776 & 24-2260
description that the victims were instructed to text him dur-
ing every “date.”
In short, there was probable cause to issue the search war-
rant because “‘known facts and circumstances’ allow[ed] a
reasonable belief that a search [would] turn up evidence of
criminal activity.” Id. at 1065 (quoting United States v. Brack,
188 F.3d 748, 755 (7th Cir. 1999)).
B
Mr. Jackson also contends that the district court erred
when it denied his motion for a Franks hearing. We review the
denial of a Franks hearing for clear error, but we “review de
novo any legal determinations that factored into the district
court’s decision.” United States v. Maxwell, 143 F.4th 844, 854
(7th Cir. 2025).
Before the district court, Mr. Jackson contended that he
was entitled to a Franks hearing. These hearings explore the
validity of a search warrant affidavit. Franks grants a criminal
defendant the limited right to challenge the veracity of state-
ments made in an affidavit supporting a search warrant.
Franks v. Delaware, 438 U.S. 154, 155–56 (1978). If a defendant
makes a “substantial preliminary showing that a false state-
ment knowingly and intentionally, or with reckless disregard
for the truth, was included by the affiant in the warrant affi-
davit, and if the allegedly false statement is necessary to the
finding of probable cause, the Fourth Amendment requires
that a hearing be held at the defendant’s request.” Id. The clear
error standard of review also applies when, as here, the de-
fendant challenges the affidavit on the ground that key facts
were omitted. United States v. Hancock, 844 F.3d 702, 707–08
(7th Cir. 2016).

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Nos. 24-1776 & 24-2260 9
Mr. Jackson submits that he was entitled to the hearing be-
cause the affidavit omitted all mention of AV-4’s initial denial
that anything was wrong. To be granted a Franks hearing,
however, a defendant must make a “substantial preliminary
showing” that the affidavit contained a material omission,
that the affiant made the omission intentionally or recklessly,
and that the omission was necessary to support the finding of
probable cause. United States v. Maro, 272 F.3d 817, 821 (7th
Cir. 2001) (emphasis added) (quoting Franks, 438 U.S. at 155–
56). The district court decided that the omitted facts were not
material to the finding of probable cause. When Officer
Pittman first questioned AV-4, she had just been choked to
the point of passing out and was in the presence of another
woman involved in Mr. Jackson’s operation. Once Officer
Pittman separated her from the other woman, she began an-
swering questions in “substantial detail.”8 We agree with the
district court that “[t]he fact that she denied involvement at
first does not make her later statements untrustworthy.”9
“[A]n omitted fact is material if its inclusion would have
negated probable cause.” Hart v. Mannina, 798 F.3d 578, 592
(7th Cir. 2015) (quoting Whitlock v. Brown, 596 F.3d 406, 411
(7th Cir. 2010)). To make that determination, we “examine
whether a hypothetical affidavit that included the omitted
material would still establish probable cause.” Id. at 593 (quot-
ing United States v. Robinson, 546 F.3d 884, 888 (7th Cir. 2008)).
The affidavit would still have established probable cause if it
included AV-4’s initial statements to Officer Pittman. AV-4, a
sex crime victim, initially denying involvement in criminal
8 R.79 at 10.
9 Id.

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10 Nos. 24-1776 & 24-2260
activity did not negate the probable cause created by her later
statements affirming them, especially considering that one of
the other women in the trafficking ring had been interjecting
herself into the officer’s questioning of AV-4. AV-4 had also
just been choked to unconsciousness by Mr. Jackson. The af-
fidavit shows that AV-4 provided extensive and thorough de-
tail on her experience with Mr. Jackson and the methods that
the trafficking victims used to meet men, both in Waukesha
and in Milwaukee. Even if Detective Stucker had included
AV-4’s initial report that no one had hurt her beyond stealing
her belongings, that inclusion would not have negated prob-
able cause.
Detective Stucker omitted statements that would have
had, at best, a minor exculpatory effect. Notably, he also omit-
ted evidence that would have strengthened the affidavit, such
as that Mr. Jackson’s choking of AV-4 was caught on a pole
camera and that a bystander saw Mr. Jackson accost her. In
any event, when viewed in their totality, these omissions are
not egregious and certainly manifest no reckless disregard for
the truth. The affidavit, crafted to establish probable cause,
understandably focuses on the high level of detail that AV-4
provided investigators, including the specific color and inte-
rior of Mr. Jackson’s car; his purchases at a gas station in a
particular town; the floor of their hotel room at a casino;
Mr. Jackson’s address; the prices for all of the acts of sexual
contact that the victims were expected to perform; the rules
the victims had to follow; the website on which Mr. Jackson
posted an escort advertisement of AV-4; the exact number
and length of “dates” AV-4 had; and the exact number of

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Nos. 24-1776 & 24-2260 11
times AV-4 went to Milwaukee to attempt to engage in com-
mercial sex acts.10
Mr. Jackson contends that the district court made conclu-
sory statements unsupported by the affidavit, such as noting
that AV-4’s “initial denials are thus hardly surprising” given
that she had “just been choked to the point of unconscious-
ness ….”11 He also asserts that the district court engaged in
“mere speculation” when it wrote that AV-4 “opened up” to
police as a result of Officer Pittman separating her from the
other woman.12 These objections are without merit. The dis-
trict court hardly engaged in impermissible speculation; ra-
ther, it properly assessed the materiality of each omission by
considering whether, had the omission been included, there
would still have been probable cause. Id. at 593.
Mr. Jackson also argues that the affidavit contained no cor-
roboration of AV-4’s inculpatory statements. He invites our
attention to United States v. Glover, 755 F.3d 811 (7th Cir. 2014).
There, we determined that a defendant was entitled to a
Franks hearing after a magistrate judge granted a search war-
rant supported by an affidavit based solely on the statement
of a police informant. We deemed the affidavit insufficient be-
cause it contained no information about the informant’s cred-
ibility. Id. at 816.
We have a very different situation here. The Glover inform-
ant had a prior criminal record (including while acting as an
informant), and he engaged in gang activity, thus raising the
10 R.55-3 at *6–9.
11 R.79 at 10.
12 Appellant’s Br. 32; R.79 at 10.

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12 Nos. 24-1776 & 24-2260
possibility that gang rivalries motivated his information. Pre-
viously, he also had used aliases to deceive the police and ex-
pected payment for his information. Id. at 817. The inform-
ant’s statements also “provided little detail.” Id. By contrast,
AV-4 was a victim of the criminal activity under investigation.
Her statements were based on her first-hand knowledge as
one of the victims of the trafficking ring, not as an outside,
rival gang member. There is no suggestion that she expected
payment for her statements. While police “confirmed only mi-
nor facts and legal conduct” in Glover, id., here, police con-
firmed from pole camera footage that AV-4 had been choked
to unconsciousness by Mr. Jackson. AV-4’s initial denials of
criminal wrongdoing were not material to the probable cause
determination.
Ultimately, Mr. Jackson cannot make a substantial prelim-
inary showing of a material omission that would alter the
probable cause determination or of a deliberate or reckless
disregard for the truth.
C
We come to Mr. Jackson’s contention that the district court
erred by allowing the Government’s expert to testify. The ad-
mission of expert testimony is governed by Daubert v. Merrell
Dow Pharm. Inc., 509 U.S. 579 (1993), and Federal Rule of Evi-
dence 702. Rule 702 requires that expert testimony assist the
trier of fact and demonstrate sufficient reliability. United States
v. Johnson, 916 F.3d 579, 586 (7th Cir. 2019). “We employ a two-
step standard of review in cases challenging a district court’s
admission or exclusion of the testimony of an expert.” C.W. ex
rel. Wood v. Textron, Inc., 807 F.3d 827, 835 (7th Cir. 2015). First,
we review de novo the district court’s application of the Daub-
ert framework. Then, if the district court properly applied

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Nos. 24-1776 & 24-2260 13
Daubert, we review for abuse of discretion its decision not to
exclude expert testimony. Johnson, 916 F.3d at 586.
The approach mandated by Daubert applies to testimony
based not only on “scientific” knowledge, but also on “tech-
nical” and “other specialized” knowledge. Kumho Tire Co.,
Ltd. v. Carmichael, 526 U.S. 137, 141 (1999). We have applied
the methodology to the social sciences. See Tyus v. Urban
Search Mgmt., 102 F.3d 256, 263 (7th Cir. 1996) (“We have
noted a number of times since the Supreme Court decided
Daubert that its framework for assessing expert testimony is
applicable to social science experts, just as it applies to experts
in the hard sciences.” (collecting cases)).
No matter the context, a court must always “act as a vig-
orous gatekeeper to ensure the reliability of expert testimony
….” Howard v. Cook Cnty. Sheriff’s Off., 989 F.3d 587, 601 (7th
Cir. 2021) (quoting Robinson v. Davol Inc., 913 F.3d 690, 696
(7th Cir. 2019)). “In all cases,” the trial court “must ensure that
it is dealing with an expert, not just a hired gun.” Tyus, 102
F.3d at 263.
1
While this case was in the district court, the Government
filed a notice of its intent to introduce the expert testimony of
Christa Jane Anderson at trial.13 Anderson is a former prose-
cutor of human trafficking cases and at the time was a senior
attorney adviser at a nonprofit organization focused on pros-
ecution practices related to gender-based violence and human
trafficking.
13 See R.84.

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14 Nos. 24-1776 & 24-2260
The Government sought to have Anderson testify on thir-
teen different topics related to domestic sex trafficking, in-
cluding the “sex-trafficking and prostitution business,”
“[c]ommon, unique, and/or term-of-art terminology used in
the prostitution and sex trafficking industry,” “[t]he groom-
ing and recruitment process,” “[t]he ‘climate of fear’ sex traf-
fickers create to exploit their victims’ vulnerabilities, suscep-
tibilities, fears, or limitations,” and “[t]he reasons why sex
trafficking victims may not leave their traffickers at the first
opportunity.”14 However, Anderson would not testify about
the credibility of any victims or witnesses. She had not met
the victims, reviewed any of their statements, or reviewed any
evidence from the investigation in the case. Mr. Jackson
sought the exclusion of Anderson’s testimony. He character-
ized the proffered testimony as ipse dixit, not based on relia-
ble principles and methods.15
At the final pretrial hearing, the district court greeted the
Government’s proffer with a skepticism quite evident even on
the cold transcript. It raised multiple concerns about the pro-
posed testimony. The court began its analysis by summariz-
ing the four requirements for an expert witness to testify un-
der Rule 702. Because the Government explained that it pro-
vided Anderson no details on the facts of the case, the district
court did not consider relevant the requirement that experts
reliably apply the principles and methods to the facts of each
case. But the court emphasized that the “question that is pre-
sented here is not whether he engaged in criminal conduct
that might be called sex trafficking under state law or might
14 Id. at 4–6.
15 See R.88.

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Nos. 24-1776 & 24-2260 15
broadly be considered sex trafficking by activists or advo-
cates.”16 The court expressed the concern, however, that alt-
hough the elements of the sex trafficking crimes at issue are
set by federal law, the jury might believe that the Government
proved its case if it provided evidence of what Anderson de-
scribed as having seen in the past, instead of evidence that es-
tablishes the federal trafficking statute’s requirements. The
court also expressed concern that the Government “may be
trying to have a lawyer in the guise of an expert witness … to
reiterate its opening statement or to give a preliminary closing
statement during the evidence of the case, and that’s inappro-
priate.”17 And “this is a social science type expert, who is a
lawyer by training, not a social scientist.”18
The court continued to express the same cautious skepti-
cism throughout the case. The court ruled that Anderson
could “testify based on her experience, subject to cross-exam-
ination, of course, with respect to issues that are presented in
this case.”19 To avoid the potential for unfair prejudice, An-
derson could testify only “subject to a factual predicate being
laid” that would “make clear what the relevant issues are.”20
Her “testimony would have to be narrowly tailored to ad-
dress those issues and to protect Mr. Jackson from any unfair
prejudice.”21
16 R.174 at 60:17–20.
17 Id. at 62:05–08.
18 Id. at 62:16–17.
19 Id. at 72:03–05.
20 Id. at 73:10–11, 72:12.
21 Id. at 72:13–15.

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16 Nos. 24-1776 & 24-2260
During trial, the district court again turned to the Daubert
issue before Anderson testified. The court asked the attorneys
if they had agreed on the admissibility of some or part of the
testimony, and it held a thorough discussion. Given the
court’s preliminary ruling, and given the Government’s ac-
quiescence to the limited scope of topics to which Anderson
could testify, Mr. Jackson’s counsel was willing to agree to
those limited topics, subject to his challenge to the testimony’s
admissibility as a whole.
The Government delineated the topics about which it
planned to ask Anderson. Specifically, these topics were, “the
role of the, quote, ‘bottom bitch,’ end quote, within a sex traf-
ficking organization”; “the reasons why sex trafficking vic-
tims may not leave their traffickers at first opportunity”; “traf-
fickers[’] use of their victims to insulate themselves from
criminal liability”; and “progressive and piecemeal disclosure
by victims of sex trafficking.”22 The court cautioned that, alt-
hough the Government could establish Anderson’s back-
ground and qualifications, it should not “gild the lily … be-
cause it could reach a point where it becomes unnecessary
and unfairly prejudicial.”23 The court went on to again cau-
tion the Government to lay a foundation and be careful in
light of Rule 403’s balancing requirement. The court also in-
structed Mr. Jackson’s attorney to object if the Government
went too far in its questioning. Mr. Jackson’s counsel did not
object during the questioning.
The court recapitulated its analysis of Daubert and sum-
marized that it had ordered the Government to establish the
22 R.192 at 1041:16–18, 1041:21–23, 1042:01–02, 1042:07–08.
23 Id. at 1043:23–24.

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Nos. 24-1776 & 24-2260 17
relevance and limited nature of Anderson’s testimony. The
court noted that one of Anderson’s potential topics was to ex-
plain the term, “bottom bitch.” The court instructed that the
term could not be used in Anderson’s testimony because it
was “inflammatory” and had not been used in the trial so
far.24 Instead, Anderson could only use the phrase “bot-
tom.”25
During trial, Anderson was the Government’s eleventh
witness. She testified after AV-2, AV-3, and AV-4, but before
AV-1. She testified to, among other things, the meaning of the
term “bottom” in sex trafficking operations.26 A “bottom” is
the individual who is the second in command in the organi-
zation.27 Anderson also explained common rules that traffick-
ers have, including with whom victims may speak and how
victims give money to the trafficker. She further explained the
level of surveillance that victims in a trafficking operation ex-
perience. Anderson agreed that it was “incredibly uncom-
mon” for “victims of sex trafficking to disclose everything
that’s happened to them by the trafficker immediately[.]”28 In
“[e]very single case,” victims who are out in a public area do
not disclose their situations to someone right away.29 Shame,
fear, the trafficker’s instruction not to trust anyone, and
“years and decades of history [in which] victims of trafficking
24 Id. at 1047:03–05.
25 Id. at 1047:09–12.
26 Id. at 1119:13–16.
27 Id.
28 Id. at 1123:14–18.
29 Id. at 1124:22.

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18 Nos. 24-1776 & 24-2260
have been treated like criminals” cause victims not to disclose
immediately to law enforcement that they are victims.30
Mr. Jackson’s attorney did not object to the Government’s
questioning of Anderson. On cross-examination, Mr. Jack-
son’s attorney focused on differentiating voluntary sex work-
ers and victims of sex trafficking. He also questioned Ander-
son about her qualifications and clarified that she did not
know any details of the case at issue. The Government did not
question her on redirect.
Later in the trial, the parties discussed the jury instruc-
tions. The Government objected to giving Instruction 3.13.
This instruction related to Anderson, named her, and told the
jury that they did not have to accept her testimony and that
they should judge her opinions and testimony about sex traf-
ficking in the same manner as that of any other witness.31 The
Government opposed the instruction because “of the type of
expert opinion that was given.”32 The basis of the Govern-
ment’s objection is unclear in the record, but it lamented that
“there’s not a pattern [instruction] for a different type of ex-
pert.”33 Mr. Jackson’s attorney asked that it be given, and the
district court agreed.
2
In assessing this situation, we first must determine
whether the district court properly applied Daubert. The
30 Id. at 1126:22–1127:03.
31 R.118-1 at 6.
32 R.194 at 1572:24–25.
33 R.195 at 1823:20–21.

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Nos. 24-1776 & 24-2260 19
district court’s Daubert analysis was extensive and thorough.
It addressed the reliability of Anderson’s testimony twice,
both times in depth and in light of the requirements of Daubert
and Rule 702. “All told, such an inquiry stands in stark con-
trast to the cases” in which courts do not perform a Daubert
analysis, articulate “only a one-sentence conclusion,” or make
“conclusory Daubert determinations ….” Kirk v. Clark Equip.
Co., 991 F.3d 865, 872–73 (7th Cir. 2021) (citation modified)
(collecting cases). Accordingly, we review the district court’s
decision not to exclude Anderson’s testimony for abuse of dis-
cretion.
3
Mr. Jackson submits that Anderson was insufficiently
qualified to testify as an expert because (a) her training and
skill as a prosecutor was for a relatively short period of time,
having served eight years as a state prosecutor; (b) her meth-
odology was unclear; (c) she was a lawyer by training, not a
psychologist, despite that she testified as a social scientist; and
(d) her testimony was not based on sufficient facts and data
or reliable principles and methods. Also at issue is whether
Anderson’s testimony impermissibly bolstered the victims’
testimony.
An expert witness’s testimony may be based on “accumu-
lated expertise obtained through experience and training.”
United States v. Conn, 297 F.3d 548, 554 (7th Cir. 2002). While
courts use multiple factors to assess the reliability of expert
testimony, the “district court is free to fashion an approach
more precisely tailored to an evaluation of the particular evi-
dentiary submission before it.” Id. at 556. Here, the Govern-
ment sought to have Anderson “educate the jury about some

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20 Nos. 24-1776 & 24-2260
topics in sex trafficking operations.”34 “In certain fields, expe-
rience is the predominant, if not sole, basis for a great deal of
reliable expert testimony.” F ED. R. EVID. 702 advisory commit-
tee’s note to 2000 amendments.
Although Anderson served as a prosecutor for eight years,
she also worked at a nonprofit organization that provides
training and technical assistance to professionals working on
“intimate partner violence, stalking, sexual violence, and hu-
man trafficking.”35 At the time of trial, she was the nonprofit’s
senior attorney advisor and had worked there for nine years.
She testified that “85 percent of what I’m currently doing is
based on human trafficking,” and “of that, maybe 50% [sic]
on sex trafficking and the other on labor trafficking.”36 Alt-
hough she did not have psychology experience and was not a
clinical researcher, she did attend trainings to learn about sex
trafficking and provided training on sex trafficking topics. We
conclude that the district court acted within its discretion in
deciding that Anderon’s qualifications made her a witness ca-
pable of assisting the jury in its understanding of the case. The
situation presented by the facts of the case were, in all likeli-
hood, unfamiliar to most, if not all, members of the jury. The
proffered testimony, disciplined by the district court’s im-
posed limitations and admonitions and subject to cross-exam-
ination, had the potential of assisting the jurors. The district
court did not abuse its discretion in permitting Anderson to
testify.
34 R.192 at 1118:12–13.
35 Id. at 1116:03–04.
36 Id. at 1117:04–06.

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Nos. 24-1776 & 24-2260 21
Similarly, we cannot say that the district court abused its
discretion in admitting Anderson’s actual testimony. In other
cases, we have upheld the decision of trial courts to permit
expert testimony on issues relating to key terms in human
trafficking and typical behaviors of victims. See United States
v. Vines, 9 F.4th 500 (7th Cir. 2021); United States v. Carson, 870
F.3d 584 (7th Cir. 2017); United States v. Dingwall, 6 F.4th 744
(7th Cir. 2021); see also United States v. Young, 955 F.3d 608, 615
(7th Cir. 2020) (“The district court did not abuse its discretion
by concluding that Landau’s expert testimony, which defined
key terms and explained common sex-trafficking dynamics,
was reliable and helpful for the jury.”).
Vines upheld the admission of testimony from an FBI spe-
cial agent who testified on “the behavior of sex-trafficking vic-
tims in general” during a criminal trial of an individual ac-
cused of various counts relating to sex trafficking of a minor.
9 F.4th at 505. The agent “discussed the need to gain the trust
of sex trafficking victims” during investigations “and the un-
willingness of victims to reveal all details from the start, as
part of ongoing victim behavior.” Id. We determined that his
testimony “merely provided insight as to sex trafficking gen-
erally and the effect on victims, which would aid a jury in un-
derstanding and evaluating the evidence presented to it.” Id.
Just like Anderson, the expert in Vines never spoke to the vic-
tim and never read any of the victim’s statements, “and there-
fore his testimony could not have been interpreted as opining
as to her credibility.” Id.
In Carson, we described an expert who provided testimony
on sex trafficking in a similar manner as here. 870 F.3d at 591.
“Importantly for this case, … [the expert] explained that vic-
tims often stay with their traffickers—or leave and then

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22 Nos. 24-1776 & 24-2260
return—because they believe they have nowhere to go; that
there is no one else out there for them, and no other options
for them; they feel ashamed and guilty and stigmatized,
thinking that they will not be accepted elsewhere.” Id.
Our decision in Dingwall, although arising in a different
context, provides additional basis for comparison. 6 F.4th at
753. The defendant in Dingwall was charged with multiple
robberies. She admitted committing those robberies but
sought to raise a duress defense. She asserted that she com-
mitted the robberies “in fear of brutal violence at the hands of
her abusive boyfriend ….” Id. at 746. We recognized that the
Government “often introduces expert evidence to explain
how traffickers systematically and intentionally coerce their
victims by inflicting psychological control and fear” in human
trafficking cases. Id. at 753 (citing Young, 955 F.3d at 615). We
held that the district court should have afforded Dingwall the
opportunity to “offer evidence of battering and its effects, in-
cluding expert opinions, to support her duress defense” be-
cause “[s]uch evidence can help inform the factfinder how an
objectively reasonable person in her circumstances may be-
have.” Id. at 761.
Anderson’s testimony was similar to that of the experts in
Vines and Carson. She explained key terms in the trafficking
world. Anderson also explained common rules that traffickers
have, including with whom victims may speak and how vic-
tims give money to the trafficker. She further explained the
level of surveillance that victims in a trafficking operation ex-
perience.
Anderson’s testimony also suggested a consideration that,
while important in assessing AV-4’s behavior, would not have
been evident to a jury with no earlier experience with human

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Nos. 24-1776 & 24-2260 23
trafficking. Mr. Jackson’s attorney’s opening statement
claimed “[t]his was voluntary prostitution,” that three of the
four “alleged victims … were arrested and they cooperated
with the Government,” giving them “a reason to lie, to not be
truthful.”37 The victims’ statements “change[d] each time”
they attended interviews with the Government.38 The victims
were “not coerced” because they would stay a few days or
weeks with Mr. Jackson and then “left voluntarily.”39 Alt-
hough the Government introduced other evidence of
Mr. Jackson’s use of force and coercion,40 Anderson’s testi-
mony, although not addressing the specific facts surrounding
AV-4’s behavior, offered an explanation as to why a victim
might still have been coerced by a trafficker even if she did
not take the first available opportunity to report her experi-
ence. For example, Anderson testified that victims may avoid
immediate disclosure to police because “they may be subject
to punishment by the trafficker,” or “other women that they
were trafficked with [may] be tasked with punishing them.”41
We also note that the district court provided a cautionary
instruction to the jury to consider Anderson’s testimony like
any other witness. The district court showed significant sen-
sitivity to the requirements of Rule 702 and Daubert, as well as
to the particular strain of applying those principles in the so-
cial science area. Our precedent supports the admission of
37 R.190 at 174:08–11.
38 Id. at 174:15–16.
39 Id. at 175:08–13.
40 Id. at 188:12–22, 190:21 (footage showing a victim being choked).
41 R.192 at 1128:16–20.

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24 Nos. 24-1776 & 24-2260
Anderson’s testimony, and the district court did not abuse its
discretion by admitting it.
4
Even if the district court had abused its discretion, allow-
ing Anderson’s testimony would be harmless error. The test
for harmless error is “whether, in the mind of the average ju-
ror, the prosecution’s case would have been significantly less
persuasive had the improper evidence been excluded.” United
States v. Jett, 908 F.3d 252, 267 (7th Cir. 2018) (citation modi-
fied). Even if Anderson had not testified, the jury had over-
whelming evidence to convict. For example, evidence from
Mr. Jackson’s phone and the phone of AV-2 showed numer-
ous communications to and from Mr. Jackson about the vic-
tims, their “dates,” and money.42 Mr. Jackson’s social media
accounts, online advertisements, and business records pro-
vided further evidence.43 The four victims each testified about
their experiences. And pole camera video confirmed that AV-
4 was choked by Mr. Jackson on August 23, 2020.44 Anderson,
in turn, did not testify about any specifics of the case because
she was never given any details about it.
Conclusion
The judgment of the district court is affirmed.
AFFIRMED
42 R.190 at 227:22–228:14 (price sheet listing sexual acts and times from
Mr. Jackson’s phone).
43 R.192 at 1159:18–21 (Mr. Jackson’s advertising of AV-1 online).
44 R.190 at 188:12–22, 190:21 (footage showing choking).

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