[DO NOT PUBLISH]

IN THE UNITED STATES COURT OF APPEALS

FOR THE ELEVENTH CIRCUIT

________________________

No. 19-13782

Non-Argument Calendar

________________________

D.C. Docket No. 1:19-cr-20101-FAM-1

UNITED STATES OF AMERICA, 

 Plaintiff-Appellee,

 versus

MARK WILLIAM UN, 

 Defendant-Appellant.

________________________

Appeal from the United States District Court

for the Southern District of Florida

________________________

(December 8, 2020)

Before NEWSOM, LAGOA, and BRASHER, Circuit Judges.

PER CURIAM: 

USCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 1 of 13
2

Mark William Un appeals the 120-month sentence he received after a jury 

found him guilty of one count of importation of cocaine into the United States and 

one count of possession with intent to distribute a controlled substance. On appeal, 

Un presents three main arguments. First, he argues that the district court abused its 

discretion by refusing to allow his expert witness, Dr. Orozco, a psychologist, to 

testify about Un’s mental illness at trial. Second, he argues that the district court 

erred when it applied a two-level sentencing enhancement for obstruction of justice 

under U.S.S.G. § 3C1.1. Third, he argues that his 120-month, above-guideline 

sentence is both procedurally and substantively unreasonable because the district 

court failed to consider his mental illness. We affirm.

I

First, we consider Un’s argument that the district court abused its discretion 

by not letting his expert witness, Dr. Orozco, testify on the subject of Un’s mental 

health issues. We review a trial court’s evidentiary rulings on the admission of an 

expert witness’s testimony for an abuse of discretion. United States v. Khan, 794 

F.3d 1288, 1297 (11th Cir. 2015). As to psychiatric testimony, we have held that 

Congress did not intend the Insanity Defense Reform Act to exclude the use of all 

psychiatric testimony to negate specific intent. United States v. Cameron, 907 

F.2d 1051, 1065 (11th Cir. 1990). Instead, we concluded that the IDRA “meant to 

preclude only the use of ‘non-insanity’ psychiatric evidence that points toward 

USCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 2 of 13
3

‘exoneration or mitigation of an offense because of a defendant’s supposed 

psychiatric compulsion or inability or failure to engage in normal reflection.’” Id. 

at 1066 (citation omitted). Psychiatric evidence that a defendant was incapable of 

forming the intent necessary for the crime charged isn’t admissible because it 

doesn’t negate specific intent. Id. But psychiatric evidence offered to negate 

specific intent is admissible when it focuses on the defendant’s specific state of 

mind at the time of the crime. Id. at 1067 (citation omitted). 

So, we distinguish between evidence that the defendant lacks the 

capacity to form mens rea and evidence that the defendant actually lacked 

mens rea at the time of the offense, with only the latter being admissible to 

negate the mens rea element of an offense. United States v. Bates, 960 F.3d 

1278, 1288 (11th Cir. 2020). In Bates, for instance, we held that the district 

court did not abuse its discretion by excluding expert psychiatric testimony 

because the defendant failed to proffer the “link” between his mental illness 

and the likelihood that, at the time of the offense, he didn’t know he was 

shooting at law enforcement officers. Id. at 1290. 

So too here. Dr. Orozco proffered testimony didn’t link Un’s mental 

illness to his mens rea (or lack thereof) at the time of the crime. The 

“Summary of Testimony/Opinion and Basis” for Dr. Orozco said that she 

would “testify that she evaluated Mr. Un and determined through testing that 

USCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 3 of 13
4

he suffers from a mental health disorder that influences his thought process, 

behavior, and emotions through delusions and paranoid ideations.” But we 

have said that “[t]he proper focus should be on the proffered link or 

relationship between the specific psychiatric evidence offered and the mens rea 

at issue in the case.” Cameron, 907 F.2d at 1067 n.31. Neither in the 

telephonic hearing before the district court nor in his briefing before this Court 

has Un established a relationship between Dr. Orozco’s proffered testimony

and his mens rea at the time he brought a couple of kilograms of cocaine from 

Ecuador into the United States. And whether he knew what he was doing at 

that time—not whether, as a general matter, Un had mental health issues—was 

the relevant question. An expert in Dr. Orozco’s position has to “provide the 

‘link’ between [the defendant’s] condition and the likelihood that, at the time of 

the offense, [the defendant] did not know he was” committing the crime at 

issue. Bates, 960 F.3d at 1290. Testimony to the effect that a defendant 

“suffers from a mental health disorder that influences his thought process, 

behavior, and emotions through delusions and paranoid ideations” is of a more 

general nature, and Un didn’t link that general testimony to his state of mind at 

the time of the crime.

We’ve previously noted that district courts have “wide latitude in 

admitting or excluding psychiatric testimony on the question of a defendant’s 

USCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 4 of 13
5

incapacity to form specific intent,” Cameron, 907 F.2d at 1061 (quoting United 

States v. Twine, 853 F.2d 676, 679 n.1 (9th Cir. 1988)), and that remains true 

today. Because the testimony, as proffered, failed to provide the necessary 

“link” to his specific state of mind at the time of the crime, we can’t say the 

district court abused its discretion by excluding it. Bates, 960 F.3d at 1290; 

see also Cameron, 907 F.3d at 1067. Accordingly, we affirm Un’s 

convictions.1

 

1 Un also briefly contends that the exclusion of his expert’s testimony violated his right to 

present a complete defense. See, e.g., Crane v. Kentucky, 476 U.S. 683, 690 (1986) (“Whether 

rooted directly in the Due Process Clause of the Fourteenth Amendment, or in the Compulsory 

Process or Confrontation Clauses of the Sixth Amendment, the Constitution guarantees criminal 

defendants a meaningful opportunity to present a complete defense.”) (citations and quotation 

marks omitted). Un doesn’t seem to have raised this issue before the district court, so plain-error 

review likely applies, United States v. Camacho-Ibarquen, 410 F.3d 1307, 1315 (11th Cir. 2005), 

and Un may have abandoned the issue through inadequate briefing before this Court, see United 

States v. Jernigan, 341 F.3d 1273, 1284 n.8 (11th Cir. 2003). In any event, we have considered 

Un’s complete-defense argument and find no constitutional infirmity in the district court’s 

decision. “As the Supreme Court explained, ‘the Constitution leaves to the judges who must 

make these [admissibility] decisions wide latitude to exclude evidence that . . . poses an undue 

risk of . . . confusion of the issues.’” United States v. Mitrovic, 890 F.3d 1217, 1226 (11th Cir.

2018) (quoting Crane, 476 U.S. at 689–90), cert. denied, 139 S. Ct. 267 (2018). That risk can be 

present where an expert’s testimony concerning “psychiatric evidence . . . present[s] a 

dangerously confusing theory of defense more akin to justification and excuse than a legally 

acceptable theory of lack of mens rea.” United States v. Cameron, 907 F.2d 1051, 1067 (11th 

Cir. 1990) (quotation marks omitted). We think the district court’s ruling here reflects an 

awareness of the risk of that kind of confusion in this case. Moreover, the Supreme Court’s 

complete-defense cases “have focused only on whether an evidentiary rule, by its own terms, 

violated a defendant’s right to present evidence.” Moses v. Payne, 555 F.3d 742, 758 (9th Cir. 

2009) (emphasis added); see, also, e.g., Holmes v. South Carolina, 547 U.S. 319, 324–26 (2006) 

(describing various “‘arbitrary’ rules, i.e., rules that excluded important defense evidence but that 

did not serve any legitimate interests”). And Un’s quarrel is not with a rule, but a ruling. Sound

as that ruling was, we reject Un’s invitation to declare it a violation of his right to a complete 

defense. 

USCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 5 of 13
6

II

Now, we turn to the two-level sentencing enhancement for obstruction of 

justice. Pursuant to U.S.S.G. § 3C1.1A, a defendant’s offense level can be 

enhanced by two levels if he willfully obstructed or impeded, or attempted to 

obstruct or impede, the administration of justice with respect to an investigation, 

prosecution, or sentencing of his offense. United States v. Guevara, 894 F.3d 

1301, 1311 (11th Cir. 2018). We review the district court’s factual findings for 

clear error and its application of those facts to the sentencing guidelines de novo. 

Id. And we accord special deference to the district court’s credibility 

determinations. United States v. Banks, 347 F.3d 1266, 1269 (11th Cir. 2003). 

A defendant obstructs justice when he commits perjury, which is “false 

testimony concerning a material matter with the willful intent to provide false 

testimony, rather than as a result of confusion, mistake, or faulty memory.” United 

States v. Duperval, 777 F.3d 1324, 1337 (11th Cir. 2015) (quotation marks 

omitted). Testimony is material where, if believed, it would tend to influence or 

affect the issue under determination. U.S.S.G. § 3C1.1, cmt. n.6. Typically, 

material testimony goes to the issue of the defendant’s guilt. See United States v. 

McKinley, 732 F.3d 1291, 1298 (11th Cir. 2013). We accord deference to a district 

court’s finding that the defendant committed perjury, as it tends to require “a 

USCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 6 of 13
7

particularized assessment of the credibility or demeanor of the defendant.” United 

States v. Williams, 340 F.3d 1231, 1241 (11th Cir. 2003). 

A district court is not required to make specific findings identifying the 

materially false statements individually; it’s enough for the district court to make a 

general finding of obstruction encompassing all the factual predicates of perjury. 

Duperval, 777 F.3d at 1337. The factual predicates for a finding of perjury include 

findings that the testimony was (1) under oath, (2) false, (3) material, and (4) given 

with the willful intent to provide false testimony. United States v. Singh, 291 F.3d 

756, 763 (11th Cir. 2002). A sentencing judge has the authority to enhance a 

defendant’s offense level when the judge makes an independent finding that the 

defendant willfully lied during trial testimony. United States v. Husky, 924 F.2d 

223, 224–25 (11th Cir. 1991) (holding that the district court’s finding that the 

defendant “told a story . . . meaning a lie, and it was deliberate” was a sufficient 

independent finding); see also United States v. Jones, 32 F.3d 1512, 1520 (11th 

Cir. 1994) (holding that an obstruction enhancement was appropriate where a 

district court determined that the defendant’s obstruction was “absolutely clear”). 

Here, the district court concluded that a two-level sentencing enhancement 

for obstruction of justice was proper because Un’s testimony at trial was “simply 

not true.” Though the district judge recognized that Un had “some issues having to 

do with delusion,” he concluded that Un’s “testimony during the trial was . . . 

USCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 7 of 13
8

false.” Addressing Un, the district judge said, “You did know what you were 

doing.” So, the district court appeared to reason, Un’s testimony—given under 

oath—about his “lack of knowledge” was false, and because Un’s knowledge of 

his crime was front and center at trial, false testimony on the issue was obviously 

material. And the judge expressly said that this determination was his,

“independent[] of the jury.” That’s “an independent factual determination that 

appellant repeatedly lied during his trial testimony,” Husky, 924 F.2d at 225, and it 

supports the sentencing enhancement the district court chose.

As an appellate court, we recognize that we review a cold record, and “only 

the trial judge can be aware of the variations in demeanor and tone of voice that 

bear so heavily on the listener’s understanding of and belief in what is said.”

Anderson v. City of Bessemer City, 470 U.S. 564, 575 (1985). In light of the 

institutional advantage the district court enjoys in assessing the defendant’s 

testimony, we give great deference to the district court’s determination that the 

defendant committed perjury. Williams, 340 F.3d at 1241. And we conclude that 

the district court here did not clearly err by finding that Un had obstructed justice 

through false testimony because the district court made a sufficient independent 

finding that encompassed all factual predicates of perjury. See Duperval, 777 F.3d 

at 1337; see also Husky, 924 F.2d at 224. 

USCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 8 of 13
9

III

Next, we consider Un’s arguments that his sentence was substantively and 

procedurally unreasonable. We review the reasonableness of a sentence under a 

deferential abuse-of-discretion standard. See Gall v. United States, 552 U.S. 38, 41 

(2007). When reviewing a sentence, we will first ensure that the district court 

committed no significant procedural errors, including failure to consider the 18 

U.S.C. § 3553(a) factors. Id. at 51. 

The district court is not required to state that it has evaluated each § 3553(a) 

factor individually. United States v. Ortiz-Delgado, 451 F.3d 752, 758 (11th Cir. 

2006). In the same vein, we have held that although a district court failed to state

explicitly that it considered the § 3553(a) factors, the sentence it gave was 

nonetheless reasonable because the district court considered several of the 

sentencing factors. United States v. Dorman, 488 F.3d 936, 944 (11th Cir. 2007). 

The district court’s explanation of a sentence may be brief and may derive 

substance from the context of the record, the defendant’s history and 

characteristics, and the parties’ arguments. Rita v. United States, 551 U.S. 338, 

356–58 (2007). In general, the further a sentence falls outside the guideline range, 

the more compelling a district court’s explanation must be. Gall, 552 U.S. at 47, 

50. That said, an “extraordinary” justification is not required for a sentence that is 

outside the guideline range. Id. at 47. We may not presume that a sentence outside 

USCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 9 of 13
10

of the guidelines is unreasonable and generally must defer to the district court’s 

decision that the § 3553(a) factors justified the extent of the variance. United 

States v. Irey, 612 F.3d 1160, 1187 (11th Cir. 2010) (en banc). The district court 

must explain the sentence with enough detail to show that it has considered the 

arguments of the parties and has a reasoned basis for its decision. Rita, 551 U.S. at 

356. 

If the district court’s sentence is procedurally sound, then we will review the 

sentence’s substantive reasonableness for an abuse of discretion. Gall, 552 U.S. at 

51. We will vacate a sentence only if we are left with a definite and firm 

conviction that the district court clearly erred in its consideration of the § 3553(a) 

factors. United States v. Croteau, 819 F.3d 1293, 1309 (11th Cir. 2016). The 

weight given to any of the § 3553(a) factors is committed to the sound discretion of 

the district court. Id. A sentence that is well below the statutory maximum “points 

strongly to reasonableness.” United States v. Nagel, 835 F.3d 1371, 1377 (11th 

Cir. 2016). The burden rests on the party challenging the sentence to show that it

is unreasonable in light of the record, the § 3553(a) factors, and the substantial 

deference afforded to the sentencing court. See United States v. Rosales-Bruno, 

789 F.3d 1249, 1256 (11th Cir. 2015) (citation omitted). 

Un’s sentence was not procedurally unreasonable. Un faults the district 

court for failing to “meaningfully consider” his mental illness and other mitigating 

USCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 10 of 13
11

factors. And Un contends that the district court “relied exclusively” on his prior 

arrest in Hong Kong for drug smuggling for his upward variance. The record 

refutes both contentions. 

For one thing, the district judge expressly considered Un’s mental illness. 

“You obviously, in my opinion, have some issues having to do with delusion, . . . 

and that would normally be a mitigating circumstance.” In light of other 

considerations, the district judge didn’t find that Un’s mental illness to be a 

mitigating factor here—but whether that’s right or wrong is separate from whether 

the district judge failed to consider it at all. And the record shows the district 

court’s upward variance wasn’t based “exclusively” on Un’s Hong Kong arrest. 

Instead, the judge said, “I’m going to . . . give a slight upward variance based upon 

that prior incident [in Hong Kong] and based upon the total lack of acceptance of 

responsibility.” Un hints that there’s something improper about his lack of 

responsibility being taken into account in both the calculation of the guidelines 

range and in the decision to make an upward variance, but that isn’t so. See United 

States v. Rodriguez, 628 F.3d 1258, 1264 (11th Cir. 2010) (“[A] district court can 

rely on factors in imposing a variance that it had already considered in imposing an 

enhancement.”).

Next, Un faults the district court for not mentioning § 3553(a) or “stat[ing] 

that it considered any of the § 3553(a) factors.” But we have imposed no magicUSCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 11 of 13
12

words requirement on district courts, and it’s evident from the record that the 

district judge paid careful attention to several considerations—including Un’s 

prior, similar uncharged conduct in Hong Kong, as well as his likelihood of 

recidivism and his failure to accept responsibility for his actions—that line up with 

§ 3553(a) factors like the defendant’s history and characteristics, the need to deter 

future criminal conduct, and the need to protect the public from the same. See 18 

U.S.C. § 3553(a). In the past, we haven’t required district courts to recite each 

and every factor to survive procedural-reasonableness review, Dorman, 488 F.3d at

944, and we won’t do so in this case either. Un’s sentence was procedurally 

reasonable. 

It was reasonable in substance as well. We begin by noting that although the 

sentence was above the advisory guidelines range, it was far below the 40-year 

statutory maximum set by Congress. In the past, we have treated the fact that the 

sentence imposed was “well below the statutory maximum” as a telling sign of its 

substantive reasonableness, Nagel, 835 F.3d at 1377, and the 30-year gap between 

the sentence that Un received and the limit that Congress set suggests the same is 

true here. And the sentence was grounded in the various § 3553(a) factors that 

we’ve already mentioned. Whether we might have weighed them differently 

doesn’t matter: “The weight given to any specific § 3553(a) factor is committed to 

the sound discretion of the district court.” Croteau, 819 F.3d at 1309. We 

USCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 12 of 13
13

therefore conclude that Un has failed to meet his burden to show that his sentence 

was unreasonable in light of the record, the § 3553(a) factors, and the substantial 

deference afforded to the district court. See Rosales-Bruno, 789 F.3d at 1256. 

Accordingly, we affirm Un’s 120-month total sentence. 

AFFIRMED. 

USCA11 Case: 19-13782 Date Filed: 12/08/2020 Page: 13 of 13