United States Court of Appeals
                              FOR THE EIGHTH CIRCUIT
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                                    No. 06-2961
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United States of America,                *
                                         *
      Appellee,                          *
                                         *
      v.                                 *    Appeal from the United States
                                         *    District Court for the
Mark Lou Meyer,                          *    Northern District of Iowa.
                                         *
      Appellant.                         *
                                         *
                                         *
                                 ________________

                            Submitted: February 13, 2007
                                Filed: April 25, 2007
                                ________________

Before O’CONNOR * , Associate Justice (Ret.), WOLLMAN, and SMITH, Circuit
Judges.
                            ________________


O’CONNOR, Associate Justice (Ret).

     Mark Lou Meyer appeals the district court’s revocation of his probation.
Because the district court’s factual findings on the two grounds on which it justified



      *
      The Honorable Sandra Day O’Connor, Associate Justice of the United States
Supreme Court, (Ret.), sitting by designation, pursuant to 28 U.S.C. § 294(a).
revoking Meyer’s probation were not clearly erroneous, we affirm the judgment
below.

                                           I.

       On January 22, 2004, Mark Lou Meyer was indicted for being an unlawful drug
user in possession of a firearm, in violation of 18 U.S.C. § 922(g)(3). After Meyer
pleaded guilty to this charge, the district court sentenced him to a term of three years’
probation on September 2, 2004. As relevant to this appeal, Meyer’s probation came
with two conditions. First, Meyer was prohibited from possessing or using unlawful
drugs. Second, Meyer was prohibited from leaving Iowa’s Northern District without
first obtaining permission from a probation officer or the court.

       While he was on probation, Meyer participated in two distinct methods of drug
testing. Under the first method, a probation officer affixed sweat patches to Meyer’s
skin to monitor whether he was using illegal drugs. The sweat patch technology at
issue here is a relatively novel drug testing device. The sweat patch, which is
“marketed by PharmChem, Inc., is composed of an absorbent pad and an outer
membrane. After the skin is cleaned with alcohol, the patch is applied to the wearer[],
and the absorbent pad collects the wearer’s sweat, over a period of a week or more.”
United States v. Bentham, 

, 473 (S.D.N.Y. 2006). “The [wearer]’s
sweat wets the pad, the water in the sweat eventually evaporates through the non-
occlusive membrane, and any drugs remain in the absorbent pad. Once the sweat
patch is removed from the [wearer], it is returned to PharmChem for analysis.” United
States v. Snyder, 

, 58 (N.D.N.Y. 2002). “If the absorbent patch is
removed from the skin, it cannot be reattached.” 

has been ‘cleared’ by
the Food and Drug Administration for use as a drug testing device and is used widely
in the criminal justice system because of its perceived advantages over other forms of
drug testing, e.g., its non-invasiveness, resistance to intentional adulteration, and



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ability to detect drug-use over relatively long periods.” 

.

        Beginning in November 2005 and ending in June 2006, Meyer submitted some
sixteen sweat patches for drug testing. The first seven patches that Meyer submitted
revealed no illegal substances. Because the eighth patch that Meyer submitted
somehow managed to come dislodged from his skin, the district court declined to treat
it as a drug test (even though this patch did, in fact, test positive for cocaine). Each of
the remaining eight patches that Meyer submitted tested positive for cocaine and
benzoylecgonine, a cocaine metabolite. The presence of benzoylecgonine indicates
that Meyer’s body had processed the cocaine.

      In addition to submitting sweat patches, Meyer simultaneously participated in a
urinalysis program while he was on probation. From March 2006 until June 2006,
Meyer submitted numerous urine samples, which were tested for controlled
substances. In contrast to the sweat patches that Meyer submitted during this same
period, none of the urine samples that Meyer submitted indicated that he had been
using unlawful drugs.

      In light of the positive sweat patch results, the United States filed a motion to
revoke Meyer’s probation on May 31, 2006. Meyer denied violating his probation by
taking illegal drugs. Accordingly, the district court held three evidentiary hearings in
June and July of 2006. Dr. Leo Kadehjian, a biochemist who holds an undergraduate
degree from the Massachusetts Institute of Technology and a doctorate from Stanford
University, testified on behalf of the government. A consultant to the Administrative
Office of the United States on drug testing, Dr. Kadehjian testified that the sweat
patch was a scientifically reliable device. While he acknowledged that some academic
papers concluded that sweat patches could become contaminated without the wearer
having used drugs, Dr. Kadehjian thought that these papers did not correspond to real-
world conditions. Furthermore, Dr. Kadehjian noted that laboratories will not report a

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sweat patch as testing positive for cocaine unless a metabolite of cocaine is found,
which indicates that the wearer’s body has broken down cocaine.

       Dr. Kadehjian further explained how Meyer’s negative urine results and
positive sweat patch results could be reconciled. Because urinalysis tests will not
reveal a drug if there is less than 300 nanograms of the drug per milliliter of urine, Dr.
Kadehjian noted, it does not mean that the drug is altogether absent from a subject’s
system. Rather, a negative drug test simply means that there is an insufficient amount
of the drug in the subject’s system to trigger a positive result. In addition, whereas
sweat patches monitor the individual’s drug usage twenty-four hours per day, Dr.
Kadehjian explained that urine tests detect drugs for only about two days following
cocaine usage. Dr. Kadehjian testified that Meyer’s sweat patch results revealed a
relatively modest amount of cocaine usage, which could explain why Meyer’s urine
tests came back negative.

       Meyer declined to present expert testimony about the efficacy of sweat patches.
In an effort to explain why his sweat patch results started indicating that he had used
cocaine, Meyer offered the following:

      I’ve stayed awake at nights trying to figure out what went wrong so it would
      return a positive without having any drugs in my system, without having done
      any drugs. I can come up with one possibility, that up until that point I was
      employed by a company who hauled high-end cars, Corvettes, Mercedeses,
      Jaguars, Cadillacs, all high end stuff, stuff that was going to clients who were
      rich people. I changed [to] hauling cars that were repossessed, bought from
      auctions, they weren’t cleaned, they weren’t detailed. There would have been
      any chance and every chance for me to come in contact with contamination
      from somebody that had done drugs in their cars, touched a steering wheel,
      touched the gearshift, touched the door handle. Somebody could have been
      smoking in there. It could have been in the headliner. I came in contact with
      things like that.

Revocation Hearing Tr. at 109-10.

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        The district court also heard testimony from Lisa Feuerbach, Meyer’s probation
officer. Officer Feuerbach testified that she contacted Meyer on May 1, 2006 to
request that he provide a urine sample. Meyer informed Officer Feuerbach that he
would be unable to do so because he had taken it upon himself to travel to Illinois to
submit a hair sample for drug testing. (That hair sample, Meyer noted, ultimately
tested negative for drug usage.) Officer Feuerbach testified that Meyer had not
submitted a travel request form and further indicated that she had not given Meyer
permission to travel outside of Iowa. Although Meyer claimed that he needed to drive
to Aurora, Illinois so that a laboratory technician from Omega Laboratories could
collect a hair sample, the government introduced evidence from Omega’s website
indicating otherwise. Omega’s website explained that the company sends collection
kits to customers and that those customers are responsible for collecting and returning
the hair sample.

       On July 7, 2006, the district court issued a written opinion finding, by a
preponderance of the evidence, that Meyer had violated the conditions of his
probation in two ways. See United States v. Meyer, No. 04-CR-0010, mem. op. (N.D.
Iowa July 7, 2006). First, the district court determined that Meyer’s trip to Illinois on
May 1, 2006 violated his probation because he did not receive permission to travel
outside of Iowa’s Northern District. See 

Second, the district court found
that Meyer’s sweat patch results were in fact reliable, meaning that Meyer had
violated his probation by consuming a controlled substance. See 

The district
court revoked Meyer’s probation and sentenced him to six months’ imprisonment
followed by two years of supervised release. See 

This appeal followed.



                                           II.

       When a district court revokes an offender’s probation, we review the district
court’s factual findings for clear error. See United States v. Carothers, 

,

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1019 (8th Cir. 2003). “Revocation of probation requires only enough evidence, within
a sound judicial discretion, to satisfy the district judge that the conduct of the
probationer has not met the conditions of probation.” United States v. Leigh, 

, 1012 (8th Cir. 2002) (internal quotation marks omitted). We review the district
court’s underlying decision to revoke an offender’s probation for an abuse of
discretion. See United States v. Shangreaux, 

, 941 (8th Cir. 1990).

                                          A.

       This court has not previously expressed a view on the general reliability of
sweat patch results. In United States v. Redd, the court noted, but explicitly reserved,
the question of sweat patch reliability. See 

, 780 n.2 (8th Cir. 2003)
(“[T]his opinion should not be read as a general endorsement or rejection of sweat
patch technology.”). Courts that have weighed in on this question, however, have
concluded that the sweat patch is a generally reliable device. The United States Court
of Appeals for the Tenth Circuit, for instance, found sweat patches reliable in
monitoring drug usage where an offender did not offer evidence to counter positive
sweat patch results. See United States v. Gatewood, 

, 1060-62 (10th
Cir. 2004), vacated on other grounds, 

(2005). Federal district courts,
both within the Eighth Circuit and in other jurisdictions, have also deemed sweat
patches to be generally reliable. See 

(concluding that
sweat patch results “may sometimes be fallible, but probably not in this case”);

(“[T]he sweat patch is generally reliable for drug testing
purposes.”); United States v. Zubeck, 

, 898-99 (W.D. Mo. 2002)
(revoking defendant’s supervised release on the basis of sweat patch results where
Kadehjian offered expert testimony about the technology); United States v. Stumpf, 

, 974 (D. Nev. 1999) (“[T]his Court finds by a preponderance of the
evidence that the PharmChem sweat patch drug testing device is a reliable scientific
method for testing for the presence of controlled substances.”). These courts have
further noted, however, that there could be some instances where positive sweat patch

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results might be deemed unreliable. See, e.g., 

(“[A]lthough the sweat patch is generally reliable, it cannot be relied upon in
situations where it is shown that the possibility of exterior contamination exists due to
exposure to a basic solution containing drugs.”).

       Today, we join 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. It is important to note that the Food and
Drug Administration cleared the PharmChem sweat patch technology back in 1990.
Today, the sweat patch is a widely used method for drug testing that is authorized by
the Administrative Office of the United States Courts. We also place weight on the
expertise of Dr. Kadehjian, who vouched for the general reliability of sweat patch
results. And while sweat patches have not been exhaustively studied by scholars, the
peer-reviewed academic studies that have been conducted generally support the
device’s reliability. See 

.

       That is not to say, of course, that positive sweat patch results are invariably a
reliable indicator of drug usage. 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.

                                           B.

       In that vein, we must now determine whether the sweat patch results in this
particular case presented a valid ground for revoking Meyer’s probation. Meyer
contends that the district court erred in revoking his probationary status because the
district court’s decision was not supported by a preponderance of the evidence. While
Meyer does not dispute that eight of his sweat patches tested positive for cocaine and a
cocaine metabolite, he urges that we are required to reverse the district court’s
decision in light of his numerous negative urine samples and negative hair sample.


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      We disagree. At the outset, it is important to remember that sweat patches were
applied to Meyer (and returned for testing) without incident on seven separate
occasions, covering a period of several weeks. That the sweat patch method initially
worked adequately for Meyer would appear to rule out any possibility that he had a
physiological condition which caused the sweat patches to return false positives.

       Meyer asserts that a change in his work conditions may have caused him to test
positive for cocaine. In his capacity as an employee of a company that hauled cars,
Meyer notes that around the time that he started testing positive for cocaine that he
stopped working with luxury cars and began working with cars that had been
repossessed and auctioned. Meyer suggests that it is possible that he inadvertently
came into contact with cocaine in these automobiles, by touching steering wheels,
gearshifts, and door handles.

      Meyer’s effort to support an environmental explanation for his positive sweat
patches is wholly unpersuasive. In order to test positive not only for cocaine but also
for cocaine metabolite, Meyer would have needed to ingest cocaine residue
inadvertently from the vehicles that he hauled. Moreover, Meyer returned eight
consecutive sweat patches with positive results. And Meyer has proffered not one
whit of evidence indicating that any of the cars that he worked with contained any
amount of cocaine.

       As for Meyer’s contention that the negative urine samples demonstrate that the
district court erred in revoking his probation, Dr. Kadehjian offered a sensible
explanation of how these seemingly differing results could in fact be reconciled.
Because Meyer’s sweat patches demonstrated a relatively low level of cocaine use, the
negative urine samples could have occurred because the amount of cocaine that Meyer
consumed was simply too small to register a positive result through urinalysis. A
negative urine test does not mean that Meyer did not take cocaine; it means only that
the test did not reveal that Meyer had done so. In addition, we note that it is possible

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for individuals to escape urinalysis detection through any number of devices and
methods. See United States v. Alfonso, 

, 196 (D. Mass. 2003)
(“[B]ecause of the widespread usage of the urine tests, techniques and products have
been developed to ‘beat’ them through dilution, adulteration, and substitution.”).
Given the eight consecutive positive sweat patch results, we have no trouble affirming
the district court’s revocation of Meyer’s probation.

       Nothing in Snyder, moreover, requires us to reach a contrary result. See 

-61. In that case, the district court noted that some environments
could lead to the contamination of sweat patches: “[A]lthough the sweat patch is
generally reliable, it cannot be relied upon in situations where it is shown that the
possibility of exterior contamination exists due to exposure to a basic solution
containing drugs.” 

But the environmental conditions that the defendant
confronted in Snyder are quite distinct from those that Meyer faced. In Snyder the
district court noted, “[d]uring the time period of his positive test results, defendant
resided with his mother, an admitted crack cocaine user that smoked with her friends
in his house. Defendant also worked in an occupation where he sweated profusely on
a daily basis and often rubbed his sweat path in order to relieve the discomfort.” 

It was these facts that prompted the Snyder court to conclude that the sweat patch
results were unreliable on the facts of that particular case: “[D]efendant’s exposure to
drugs in his environment and profuse sweating is a sufficient basis for rejecting the
reliability of the sweat patch in this specific instance.” 

       In sharp contrast to the defendant in Snyder, Meyer does not contend that he
lived in a home where cocaine usage occurred, which caused him to test positive for
unlawful drugs. Neither does Meyer contend that his occupation caused him to sweat
a great deal, which the Snyder court intimated could lead to sweat patch
contamination. Rather, as discussed above, Meyer contends only that his work
brought him into contact with numerous cars which could have at least conceivably
contained cocaine. Whatever the merits of Snyder’s assertions of contamination, it is

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plain that Meyer’s assertions are considerably weaker. See 

(distinguishing Snyder because the facts in Snyder gave stronger inference to
potential contamination).

        We close by noting that the negative hair test that Meyer secured is legally
meaningless. Quite apart from the shortcomings of hair tests generally, Meyer
adduced no evidence establishing that he grew the hair that Omega tested for drugs.
Thus, even if hair tests were generally viewed as reliable indicators of drug usage
(which they are not), Meyer would have succeeded in demonstrating only that he had
somehow procured a sample of drug-free hair that belonged to someone. Thus, we
cannot conclude that the district court was clearly erroneous in its factual findings or
that it abused its discretion in revoking Meyer’s probation.

                                            C.

       Even if Meyer were correct that the sweat patches did not provide sufficiently
strong evidence to justify the district court’s revocation of his probation, he would still
not prevail in this appeal. That is because the district court offered an alternate ground
for revoking Meyer’s probation. Specifically, the district court observed that Meyer
violated his probation when he—without first obtaining permission from the court or
from a probation officer—traveled outside of Iowa’s Northern District to have his hair
tested for drugs. Although Meyer asserts that he believed he had “blanket permission”
to leave the jurisdiction, Appellant’s Br. at 6 n. 2, that belief turns out to have been
mistaken. That Meyer “only traveled outside the Northern District of Iowa one time”
does nothing to alter the fact that he violated a condition of his probation. 

at least in the context of probation, is one tim e too many. Thus, Meyer’s




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misguided efforts to exonerate himself from violating one probationary condition
succeeded only in violating another probationary condition.

      The district court’s revocation of Meyer’s probation is affirmed.

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