United States Court of Appeals
                            For the Eighth Circuit
                        ___________________________

                                No. 18-2367
                        ___________________________

                             United States of America

                        lllllllllllllllllllllPlaintiff - Appellee

                                           v.

                                      Chad Hall

                       lllllllllllllllllllllDefendant - Appellant
                                       ____________

                    Appeal from United States District Court
                   for the Northern District of Iowa - Waterloo
                                 ____________

                             Submitted: May 17, 2019
                               Filed: June 14, 2019
                                  [Unpublished]
                                  ____________

Before SMITH, Chief Judge, WOLLMAN and KOBES, Circuit Judges.
                             ____________

PER CURIAM.

      Chad Hall’s supervised release was revoked after sweat patches tested positive
for methamphetamine three times within 30 days. The district court1 sentenced him


      1
       The Honorable Linda R. Reade, United States District Judge for the Northern
District of Iowa.
to one year in prison for violating a supervised release condition prohibiting drug use.
Hall appeals his revocation, arguing his violations were not supported by a
preponderance of the evidence. We disagree and affirm the district court.

                                   I. Background
      In 2012, Hall pleaded guilty to conspiracy to distribute 100 grams or more of
heroin. The district court sentenced him to 50 months’ imprisonment and 4 years’
supervised release. In February 2014, Hall’s sentence was reduced to 40 months’
imprisonment, with the term of supervised release remaining unchanged. Hall began
supervised release on April 10, 2015. Hall’s release conditions prohibited drug use.

       On October 20, 2016, the district court revoked Hall’s supervised release after
he violated his terms of release and sentenced him to three months’ imprisonment and
three years’ supervised release. Hall’s second term of supervised release began on
January 13, 2017. On March 20, 2018, Hall’s probation officer (“the officer”) visited
him at his residence. The officer noticed a change in Hall’s appearance and asked him
if he had been using drugs. Hall denied any drug use, but remaining suspicious, the
officer ordered him to submit a urine sample. The sample preliminarily tested positive
for amphetamine, cocaine, and opiates. Later, Hall admitted to drug use but told the
officer that he was unsure what drugs he had used, though he thought he had used
cocaine. Based on this violation, the district court did not revoke Hall’s supervised
release but modified Hall’s conditions of release on March 30 to include three
weekends in jail.

       Hall was also required to begin wearing sweat patches to test for drug use.
Hall’s sweat patches were changed weekly. On April 9, 2018, the officer learned that
the patch worn by Hall from March 24–March 30 (“Patch A”) tested positive for
amphetamine, methamphetamine, and cocaine. Hall denied using any drugs since
March 19. Later, Hall admitted to also using “bath salt” on March 20 but denied any
subsequent use. However, on April 16, the officer learned that Hall’s patch from

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March 30–April 6 (“Patch B”) also tested positive for amphetamine and
methamphetamine. Hall’s April 6–April 13 patch (“Patch C”) tested positive for those
substances as well. The patches tested positive in decreasing concentrations.

       On June 18, 2018, the district court held a supervised release revocation
hearing. The hearing focused on determining whether the patches tested positive due
to new drug use since March 19 or 20 or whether the results reflected residual drugs
from March 19 or 20 usage. The district court heard testimony from Dr. Leo
Kadehjian, a toxicologist. Dr. Kadehjian concluded that Patch A reflected use of a
large dose of methamphetamine after March 19 or 20. Dr. Kadehjian could not
determine conclusively whether Patch B reflected new usage or residual drugs from
the usage detected in Patch A. Additionally, he concluded that Patch C reflected use
of a new, smaller dose of methamphetamine. Dr. Kadehjian explained that

      in the case of methamphetamine . . . all of the drug comes out in the first
      one or two days in the sweat patch, and the concentrations don’t increase
      beyond that. And so one can judge that if you have sequential positive
      sweat patches, the sequential positive results likely represent renewed
      use of drug.

Revocation Hr’g. Tr. at 13, United States v. Chad Hall, No. 6:11-CR-02046-LRR-
KEM-3 (N.D. Iowa, June 18, 2018), ECF No. 428.

       In reaching these conclusions, Dr. Kadehjian relied on his knowledge and
experience as a toxicologist, as well as scientific studies. In particular, he relied on
a “controlled dosing” study (“the Barnes study”). 

the Barnes
study administered both high and low doses of methamphetamine to the subjects. The
subjects wore sweat patches both during and after the dosing week. The Barnes study
concluded that




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      [p]atches applied 2 weeks after the drug administration week had no
      measurable [methamphetamine] following the low doses, and only 1
      positive result following the high doses. Using criteria proposed by the
      Substance Abuse Mental Health Services Administration [(SAMHSA)],
      85.7% (low) and 62.5% (high) weekly sweat patches from the dosing
      week were positive for [methamphetamine], and all patches applied after
      the dosing week were negative.

Allan Barnes et al., Excretion of Methamphetamine and Amphetamine in Human
Sweat Following Controlled Oral Methamphetamine Administration, Clin. Chem.,
54(1), 172 (2008), http://clinchem.aaccjnls.org/content/54/1/172. According to the
SAMHSA criteria, a sweat patch would only be considered “positive” for
methamphetamine if testing detected both methamphetamine and amphetamine above
a certain concentration.

       After hearing the evidence, the district court concluded that all three patches
qualified as positive tests. However, it also determined that Patches A and C reflected
new drug usage but that Patch B could reflect either new drug usage or residual drugs
from the usage detected in Patch A. Having found that Hall had committed a new
violation of his supervised release—i.e., a violation separate from that addressed in
the March 30 modification—the district court revoked Hall’s supervised release and
sentenced him to one year in prison.

                                     II. Discussion
       “We review a district court’s decision to revoke supervised release for an abuse
of discretion and the court’s underlying factual findings as to whether a violation
occurred for clear error.” United States v. Miller, 

, 914 (8th Cir. 2009)
(internal quotation omitted). A district court must find a violation of a term of
supervised release by a preponderance of the evidence. 18 U.S.C. § 3583(e)(3).




                                         -4-
       We have previously found “that sweat patch results are a generally reliable
method of determining whether an offender has violated a condition of his or her
probation.” United States v. Meyer, 

, 869 (8th Cir. 2007). Nevertheless,
district courts are to determine “on a case-by-case basis” whether a positive sweat
patch is “a reliable indicator of drug usage.” 

the district court erred in relying on Dr. Kadehjian’s testimony to
establish his supervised release violations. His main argument is that Dr. Kadehjian
misrepresented the Barnes study’s findings by testifying “that none of the participants
in the [Barnes] Study had tested positive in sweat patches worn the second week after
using methamphetamine.” Appellant’s Br. at 5. Hall claims that Dr. Kadehjian’s
testimony “was incorrect, as [1 of 5] of the participants in the study who received a
‘high’ dose of methamphetamine . . . tested positive in the second week.” 

argues Dr. Kadehjian improperly extrapolated from the Barnes study’s results because
Hall consumed higher doses of methamphetamine than the study’s participants.

        Hall’s criticism of Dr. Kadehjian’s testimony misreads the Barnes’s study.
Although the study did find that one participant tested positive for methamphetamine
in the second week, it also noted that no patches applied in the second week were
positive according to the evaluative criteria employed by the study. Those criteria
contemplated the possibility of a patch containing methamphetamine without actually
testing “positive.” Indeed, in his testimony, Dr. Kadehjian emphasized the difference
between “testing positive” and “detection.” Revocation Hr’g Tr. at 38. Hall’s second
criticism of Dr. Kadehjian also fails. To be sure, the doses administered during the
Barnes study were lower than the large dose Hall likely used on or prior to March 19
or 20. But, Dr. Kadehjian did not rely exclusively on the Barnes study. He also relied
on other studies reporting on methamphetamine users consuming high doses at high
concentrations. He also noted that the subjects in the Barnes study had reported using
high doses of methamphetamine prior to participating in the study.



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       Having reviewed the record, we find no evidence that Dr. Kadehjian
misrepresented or improperly relied upon the Barnes study. Therefore, the district
court did not clearly err in relying on Dr. Kadehjian’s testimony. In light of that
testimony, and in light of the three positive sweat patches themselves, we find the
district court did not abuse its discretion in revoking Hall’s supervised release.

                                  III. Conclusion
      The judgment of the district court is affirmed.

                      ______________________________




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