United States Court of Appeals
                             For the Eighth Circuit
                         ___________________________

                                 No. 17-1969
                         ___________________________

                              United States of America

                         lllllllllllllllllllllPlaintiff - Appellee

                                            v.

                                Tavares Montgomery

                       lllllllllllllllllllllDefendant - Appellant
                                       ____________

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

                             Submitted: April 13, 2018
                               Filed: July 23, 2018
                                  ____________

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

LOKEN, Circuit Judge.

       After serving a sentence for being a felon in possession of a firearm, Tavares
Montgomery began serving three years of supervised release. The U.S. Probation
Office filed a petition to revoke supervised release, alleging that Montgomery had
violated many conditions, including use of controlled substances. After a hearing, the
district court1 revoked supervised release and sentenced Montgomery to seven
months in prison. He appeals, arguing the court violated his right to confront
witnesses when it admitted transcripts of a drug-testing expert’s testimony in prior
cases. Reviewing for abuse of discretion, we affirm.

      In March 2017, the Probation Office petitioned to revoke Montgomery’s
supervised release. At an April 11 revocation hearing, Montgomery admitted
providing a urine sample on March 22 that tested positive for cocaine. He also
admitted using cocaine on March 18, drinking a “blocker” in an unsuccessful attempt
to thwart the March 22 urine analysis, and being placed on a sweat patch2 program
on March 30. Accepting Montgomery’s representation that he last used cocaine on
March 18, the district court adopted the Probation Office’s recommendation to
modify rather than revoke supervised release and imposed a 120-day home
monitoring condition. But the court warned Montgomery:

      Now, there’s a pending sweat patch. I am assuming . . . that you are
      representing to this Court that that is going to be a negative for drugs.
      If it is not going to be, now is the time to tell me, because if we get that
      sweat patch back and it’s positive for drugs, you will go to prison.

       On April 12 and April 19, the Probation Office filed supplements to its
previous petition to revoke, alleging three additional violations: (i) failure to
participate in substance abuse testing, based on Montgomery’s admission that he used
a “blocker” before providing his March 22 urine specimen; (ii) use of controlled
substances, based on analysis of two sweat patches he wore between March 30 and


      1
       The Honorable Linda R. Reade, United States District Judge for the Northen
District of Iowa.
      2
       A sweat patch is a drug-testing device that absorbs the wearer’s sweat; after
water in the sweat evaporates, any drugs remain in the absorbent pad for analysis.
United States v. Meyer, 

, 866 (8th Cir. 2007).

                                          -2-
April 10; and (iii) failure to truthfully answer inquiries, based on his representation
at the April 11 hearing that he had not used controlled substances after March 18.
Montgomery admitted the first violation but denied the other two.

        At the revocation hearing, the government introduced without objection four
exhibits containing lab analyses of Montgomery’s sweat patches, and documents
establishing the credentials of the officers who applied and removed the sweat
patches and their chain-of-custody during the testing process. Probation Officer Amy
Moser testified in support of the petition to revoke. Moser testified that Montgomery
was placed in the sweat patch program on March 30 at a residential reentry center,
where trained officers applied and removed the sweat patches. Moser explained that,
after a sweat patch is removed, it is sent to the Clinical References Laboratory for an
initial screen for controlled substances, which, if positive, is confirmed by a second
test. The lab analyses reported that the patch Montgomery wore from March 30 to
April 6 tested positive for cocaine and THC (the metabolite for marijuana). The patch
contained over five times the minimum detection value for cocaine. The patch he
wore from April 6 to April 10 tested positive for THC but not for cocaine.

      Montgomery had provided a urine specimen on March 22 that tested positive
for cocaine and another on March 24 that tested negative for controlled substances.
Based on her training and familiarity with enforcing drug testing requirements,
Officer Moser testified that cocaine can be detected in urine only if the cocaine use
occurred twenty-four to forty-eight hours before a sample was taken. Therefore,
Officer Moser opined, (i) Montgomery’s March 18 cocaine use would not have
caused the positive cocaine test on a sweat patch applied on March 30 and removed
on April 6, and (ii) the two positive THC sweat patch tests resulted from THC
ingested after March 24, while Montgomery was wearing the patches.

     Moser testified that she had discussed the sweat patch test results with Dr. Leo
Kadehjian, a California toxicologist who is a consultant to the Administrative Office

                                         -3-
of the U.S. Courts. Over Montgomery’s objection, Moser testified that Dr. Kadehjian
advised that research would not support the proposition that a cocaine-positive test
from the March 30 to April 6 sweat patch resulted from Montgomery’s March 18
cocaine use. On cross-examination, asked if a substance other than marijuana, such
as hemp seeds, could have triggered the THC-positive tests, Officer Moser replied
that both the parent drug and metabolic drug were present in Montgomery’s sweat
patches, suggesting that marijuana was the source of the THC. Moser testified that
Dr. Kadehjian advised that the FDA prohibits hemp seeds and hemp oil sold in the
United States from containing THC.

       After Officer Moser testified, the government offered the evidence at issue on
appeal -- transcripts of Dr. Kadehjian’s lengthy testimony in two prior Northern
District of Iowa cases addressing in detail the reliability and acceptance of sweat
patches for drug testing, and explaining how sweat-patch testing differs from other
forms of drug-detection testing, such as urine and hair tests. The government did not
advise the district court, and subsequently did not explain on appeal, the purpose for
which this testimony was offered. Overruling Montgomery’s confrontation and
hearsay objections, the district court admitted the prior testimony after balancing the
cost of making Dr. Kadehjian available for cross examination against the reliability
of his proffered testimony.

        Montgomery then testified and denied using cocaine after March 18. He
theorized that the “blocker” he took before providing his March 22 urine specimen
explained why his March 24 urine specimen tested negative for cocaine. He also
testified that hemp seeds he takes for their health benefits were the likely source of
the THC found in his sweat patches. The district court found Montgomery’s
explanations not credible, revoked his supervised release, and sentenced him to seven
months imprisonment and two years supervised release.




                                         -4-
       On appeal, Montgomery argues the district court erred in admitting into
evidence two transcripts of testimony by an expert witness who was not available for
cross-examination. “[A] defendant contesting revocation is entitled to ‘the minimum
requirements of due process,’ including ‘the right to confront and cross-examine
adverse witnesses (unless the hearing officer specifically finds good cause for not
allowing confrontation).’” United States v. Simms, 

, 731 (8th Cir. 2014)
(quotation omitted). Similarly, Rule 32.1(b)(2)(C) of the Federal Rules of Criminal
Procedure provides that, at the revocation hearing, the defendant “is entitled to . . .
an opportunity to . . . question any adverse witness unless the court determines that
the interest of justice does not require the witness to appear.” The district court “must
balance the probationer’s right to confront a witness against the grounds asserted by
the government for not requiring confrontation.” United States v. Bell, 

,
642 (8th Cir. 1986); see United States v. Protsman, 

, 981-82 (8th Cir.
2016); United States v. Harrison, 

, 423-24 (8th Cir. 2015).

        The first transcript at issue recorded Dr. Kadehjian’s June 2006 testimony to
the district court in Meyer, where he “testified that the sweat patch was a
scientifically reliable device” and “explained how Meyer’s negative urine results and
positive sweat patch results could be 

. On appeal,
placing weight on Dr. Kadehjian’s expertise, we “join[ed] the other courts that have
previously determined that sweat patch results are a generally reliable method of
determining whether an offender has violated a condition of his or her probation.”

However, we cautioned:

      There may well be certain instances where offenders offer compelling
      reasons to believe that positive test results from sweat patches are
      erroneous. District courts should make such determinations on a case-
      by-case basis.




                                          -5-


his negative urine samples demonstrated the district court erred in
revoking probation. We noted that “Dr. Kadehjian offered a sensible explanation of
how these seemingly differing results could in fact be reconciled.” 

       Here, the government’s case started with the holding in Meyer that sweat patch
results are “generally reliable” unless defendant offers “compelling reasons to
believe” they are erroneous. The government introduced documents establishing the
sweat patch results and the reliable way the sweat patches were handled, to which
Montgomery did not object, and Officer Moser’s testimony interpreting the sweat
patch results. Unless rebutted, this evidence was sufficient to establish by a
preponderance of the evidence that Montgomery violated conditions of supervised
release by using controlled substances after March 18. Dr. Kadehjian’s prior
testimony regarding the general reliability of sweat patch testing was cumulative and
unnecessary, so any error in admitting it was harmless. Montgomery’s assertion that
removing Dr. Kadehjian’s testimony “would leave no basis” for the court’s revocation
decision is factually without merit.

       Montgomery attempted to show that his sweat patch tests were unreliable
because the “blocker” explained why his March 24 urine test was negative for cocaine
and his consumption of a health food containing hemp seeds explained the presence
of THC in his sweat patches. The government did not offer Dr. Kadehjian’s prior
testimony to refute Montgomery’s theories nor rely on any portion of that testimony
for that purpose. Defense counsel argued to the district court that he would like to
cross examine Dr. Kadehjian about “comparing sweat patch and urine testing.” But
the district court need not impose on the government the “inordinate” burden and
expense of producing a California expert so that defense counsel can conduct a
fishing expedition beyond the scope of the government’s direct examination. 

. Montgomery was free to retain his own expert to explore whether
his cocaine “blocker” theory might have scientific support.



                                         -6-
       Unlike the prior testimony at issue, Officer Moser’s testimony relating what Dr.
Kadehjian said when they discussed Montgomery’s sweat patch test results was
directly relevant hearsay, offered to prove the truth of the expert’s statement that
cocaine Montgomery used on March 18 would not continue to be excreted and
detected by a sweat patch he began wearing on March 30.3 Montgomery did not
focus on this issue in the district court and does not raise it on appeal. If properly
raised and supported, the issue might have persuaded the government it did not need
Dr. Kadehjian to support Moser’s experience-based opinion. Or it would have
required the district court to balance the reliability of this specific opinion against the
burden of producing Dr. Kadehjian for cross examination in the Northern District of
Iowa, live as at the June 2006 revocation hearing in Meyer, or by video conferencing
from the Northern District of California, as Dr. Kadehjian testified in a July 2016
revocation hearing in United States v. Devos, 692 F. App’x 310 (8th Cir. 2017).

        For this reason, our decision that the district court did not abuse its discretion
in this case should not be taken as a blanket ruling that Dr. Kadehjian never has to be
produced for cross examination when his opinion is offered to support sweat patch
test results at a supervised release revocation hearing. Compare 

; United States v. Martin, 

, 448-49 (8th Cir.), cert. denied, 

(2004). No doubt, it would be impractical and inordinately expensive to
require presentation of live expert testimony to support sweat patch lab test results at
every supervised release revocation hearing. But the issue must be determined “on
a case-by-case basis.” 

.

       The judgment of the district court is affirmed.
                      ______________________________

      3
        Officer Moser’s hearsay testimony also included a statement by Dr. Kadehjian
that the FDA prohibits sale of health foods made with hemp seeds or hemp oil that
contain THC. Presumably, if challenged, the government could have established this
regulatory fact by judicial notice.

                                           -7-